Septic Tank Emptying Costs – Read This and Save Money

looking inside septic tank

If you have a septic tank or a sewage treatment plant, you will need to get it emptied regularly. This will prevent septic tank problems occurring.

Septic tank emptying costs

Septic tank emptying intervals vary depending on the size of the septic tank. As a rule, a septic tank should be emptied when the sludge level is approximately 25% of the depth in the sludge chamber. You can check to see when your septic tank needs to be emptied by checking the sludge level yourself with a dipping stick. Alternatively, you can get your local septic tank emptying company to check the sludge level.

The septic tank emptying cost will vary depending on the company you use. By using a local company for your septic tank emptying it will typically keep your costs low. It is important to always use a licensed waste collection company for your septic tank emptying. Using an unlicensed company can result in significant fines.

It is important to note that septic tank emptying after heavy rainfall will require you to immediately refill your septic tank with water. Otherwise, an empty tank can get damaged by the pressure from the surrounding wet soil or the water table. By filling it with water again immediately, the water in the tank counteracts this groundwater/soil pressure. So, septic tank emptying after rainfall is OK, but just be sure to fill with water.

Septic tank sizing

Your minimum septic tank size is determined by Environment Agency design criteria.

The septic tank sizing calculator is as follows;

Septic tank size = [P x 150L] + 2000L

P = the number of people in the house.

So, for a 6 person house the septic tank sizing calculator is as follows;

6 persons x 150L + 2000L = 2900L

This is the minimum size of septic tank you should use.

Septic tank emptying will need to be more frequent for a small septic tank when compared to a large septic tank. The septic tank emptying intervals do not change whether you have a plastic septic tank or a concrete septic tank.

A septic tank is an effective way of dealing with your sewage and wastewater in an area with no mains drainage network. A septic tank can deal with all sewage generated from within the four walls of the house. Only roof water or storm water should be prevented from entering the septic tank.

Fats, oils and grease

Many types of waste like fats oils and grease [FOG] should also be prevented from entering your septic tank. Many septic tank emptying companies will not want to empty your septic tank if it is full of grease, as they may not have a license to collect greasy water. This can result in an increase in your septic tank emptying costs. So, it is important to always have a grease trap through which your kitchen wastewater should pass.

After your septic tank emptying, always check to make sure the lids of your septic tank are secure. As a septic tank without a good lid can pose a danger. It is recommended that your septic tank should be located in a fenced off area.

Included in your septic tank emptying cost is often a report of a septic tank inspection. Septic tank emptying after work and reporting can include an assessment of your tank. This can include confirmation that the baffle wall is in place and intact, confirmation that all T-pieces are in place and confirmation that there is no water ingress along joints.

Why empty your septic tank

Emptying your septic tank is an essential part of your home maintenance work. While your septic tank is underground and out of sight, failure to empty your septic tank regularly can result in major issues. These include pollution of neighbouring lands, backed up sewers preventing you from using the toilets, and soakaways or percolation areas becoming totally blocked with sludge. So, while a septic tank emptying cost is not cheap, the possible issues that can be caused by a failing septic tank are serious. Septic tank replacement costs far outweigh those of getting your septic tank emptied.

The final point to note is that septic tank emptying and sewage treatment plant emptying must be done by a professional. This is due to the health and safety risks involved with working around septic tanks. You should know the make and model of your septic tank or sewage treatment plant. Always keep a copy of the manual at home. This manual should be shown to your septic tank emptying company so that they can read the manufacturers recommendations to make sure no damage is done during septic tank emptying. (R)® – Online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice – illustrated, detailed, authoritative research on finding, diagnosing, testing, correcting, & preventing building defects, energy conservation, & indoor environmental hazards. Unbiased information, no conflicts of interest.

Containerized Wastewater Treatment

containerised wastewater treatment plant for industrial sewage treatment

Containerized sewage treatment plants are sea containers that have wastewater treatment equipment preinstalled. The benefit of a containerised wastewater treatment plant is that it is an effective method of transporting a complete wastewater treatment system to any location via sea transport. Also, containerised solutions are a form of mobile wastewater treatment, so the plant can be reused and transported to a new location when necessary.

Example application: Mobile worker camp serving the installation of oil/gas pipeline. A containerised wastewater treatment plant can be delivered by road transport to the worker camp and made operational in <12 hours. As the worker plant moves along the pipeline route, the mobile containerised sewage treatment plant can simply be moved with the worker camp.

Biocell containerised wastewater treatment plants  offer an ideal solution for applications including the following;

  • Mobile worker camps – oil and gas
  • Temporary industrial sites
  • Construction sites
  • Sites with spatial constraints as containers can be stacked
  • As temporary treatment, while municipal plants are being upgraded
  • Municipal wastewater treatment [permanent and temporary]
  • Refugee camps
  • Military camps
  • Offshore facilities

Various configurations are possible, with single containerised systems for smaller applications, and modular containerised wastewater treatment solutions comprising multiple containers for larger applications. Systems are available in standard models, or bespoke solutions can be tailored to a client’s specific requirements. Pump stations can be supplied also to pump collected wastewater to the container plant.

Packaged containerised plants can incorporate primary treatment, biological treatment, clarification and tertiary treatment into a single container. Alternatively, stand alone containerised reactors are available for biological treatment only.

We offer international delivery of containerised wastewater treatment plants. Our products have the appropriate certifications and technical approvals for all jurisdictions. Contact us now for an immediate quotation.

Septic Tank Odour

bad smell illustration

We regularly get asked about how to solve the problem of a smelly septic tank purchased from a competitor, and how our systems manage to operate without producing odour. Here we try to briefly give some advice.

Possible Causes of Septic Tank Odour

There are a number of possible causes of odour. The first possible cause is where large volumes of material that should not enter a sewage treatment plant make their way into your system. A good example is grease. An overflowing grease trap or a poorly installed grease trap can allow large volumes of fats, oils and grease [FOG’s] to enter a tank. Grease and oil can clog pipes and build up in a tank resulting in performance issues. FOGs can also result in a very bad smell by allowing anoxic conditions to form, and by causing toxic shock and killing the good bacteria in your septic system. So by making sure that only permitted substances enter your wastewater treatment plant, you can minimise the risk of septic tank odour.

The main cause of odour relates to the actual treatment process. Most systems on the market use an aerator to mix air into the wastewater. This air then provides a source of oxygen for the bacteria to grown and break down contaminants in the wastewater. But this air must then exit the tank. Poorly designed tanks do not allow this air to travel back the sewers and to then exit via the soil vent stack. If the air cannot travel back to the house and up the soil vent pipe for dispersal into the atmosphere at roof level, the air containing odour leaks out of the tank and nearby manholes causing a smell. All of our systems like the Biocell QuickOne are designed to prevent odour and to make sure air is ventilated correctly. This is why our systems are recognised as ‘odour free’ and are so popular with installers.

Another cause of bad septic tank smells can be a situation where there is no soil vent stack present at the house. The soil vent pipe is a pipe that runs up the side of a building and terminates at the roof level. As air passes over this pipe opening at roof level, it creates a chimney effect, drawing air out of the sewers and up the soil vent pipe. If you do not have a soil vent pipe, then by installing one you can help deal with any odour issues you may have. The soil vent stack should be positioned at the final manhole around the building where the sewer goes in the direction of your septic tank or sewage treatment plant. Larger buildings may need multiple soil vent pipes. Soil vent stacks should be regularly checked for blockages. If you are in an area that is very sheltered and the air existing the soil vent pipe cannot get away, we can offer activated carbon filters to place on soil vent stacks to neutralise the odour.

Solutions For Odour Problems

Some companies will offer a quick fix solution for smelly septic tanks, such as enzymes and bacteria. Our advice is ‘buyer beware’. If you have a problem it’s better to identify the cause rather than trying a quick short-term fix with no guarantees.

If you get a smell of sewer gas in a building then you should exit the building immediately and call for professional advice. Sewer gas is extremely dangerous if it builds up in an unventilated area and can result in serious illness and even suffocation/death. Incorrectly installed traps and seals on toilets, sinks, showers, etc. can also allow sewer gas to enter a building. Similarly, a soil vent pipe terminating close to an upstairs window can also allow this ventilated air from the sewers to get back into a building when the window is open.

So if you are installing a new sewage treatment plant – choose a Biocell system for guaranteed odour free operation.

UK Soakaway Design

percolation area septic tank lateral lines

The effluent leaving an onsite sewage treatment system must discharge to a soakaway or to a watercourse/drain.

All Biocell sewage treatment plants can discharge direct to a drain, stream or watercourse (due to the high standard of effluent treatment) but if a site has no access to a stream or drain, you must construct a suitable soakaway. When planning a soakaway, it is important to remember that the aim is to facilitate the filtration of final effluent through the ground.

A typical domestic system serving a household of 4-8 people produces 600-1200l of treated effluent per day. This is the typical volume the soakaway needs to accommodate. When designing a soakaway, it is important to have information on the permeability of the soil onsite. For example, if you have low permeability clay based soil then the infiltration rate will be low and you will require a large soakaway. Whereas if the soil is very sandy with a high infiltration rate, you can install a small soakaway.

Infiltration Test

The first step in designing a soakaway is to conduct a percolation test. The tank to soakaway outlet is generally 300-700mm below ground level, so we suggest carrying out the percolation test at this level in the subsoil. This gives a representative example of the soil infiltration rate at the depth the effluent will be entering the soakaway.

How to Do a Percolation Test

To do a percolation test, begin by digging a small square hole (300mm x 300mm x 400mm) into the subsoil at the level of the sewage treatment plant outlet pipe. Then fill the hole with water; allow the first fill of water to soak into the soil in order to saturate it. Once saturated, refill the hole with water.  Measure the time it takes for the water level to drop 100mm in the hole. Divide this by 4 to give the infiltration rate in minutes per 25mm.

A worked example is as follows;

1 – Hole pre-soaked overnight

2 – Hole filled with water

3 – Time recorded for water to drop 100mm – 120mins

4 – Time divided by 4 = 120min/4 = 30mins

5 – Result = 30mins/25mm = 30

The table below shows the typical amount of trench required for the number of people in a house depending on the test results achieved.

No. People Trench length
result of 0-25
Trench length
result of 25-50
Trench length
result of 50-75
4 12m 24m 36m
6 18m 36m 54m
8 24m 48m 72m
10 30m 60m 90m

Warning: Just digging a pit and filling it with gravel is not a good way of installing a soakaway. A pit style soakaway has less surface area for infiltration of the effluent into the soil and has no facility for future access [rodding and maintenance]. There is also no ventilation with a pit style soakaway for bacteria in the soil to help break down any small solids that enter the soakaway. This means a pit style soakaway can blckly and then need total replacement.

Below is a typical cross section of a trench. A trench is filled with gravel, with a 4” rigid sewer pipe with holes drilled in it. The gravel is covered with a geotextile before it is filled with soil. A trench is typically 300mm wide with a minimum of 300mm depth of gravel in the trench but this can vary.

A percolation trench should be a maximum of 10m long. So, if for example, you need 36m of trench, you would install 4 x 9m long trenches [total of 36m]. A typical trench layout is shown below. Trenches should be a minimum of 1m apart up to a maximum of 2.45m. Vents at the ends of trenches allow for ongoing inspection and maintenance. Below is a typical plan view of a percolation area.

Please note that soakaway tunnels of crates offered by some suppliers should not be installed for sewage effluent disposal. These are only certified for use with rainwater runoff. Installing them will result in non-compliance with the building regulations.

For recommended minimum separation distances between a soakaway and a dwelling, roadway, watercourse, etc – please contact your local building control office.

NOTE: This is a general guide only and we would always recommend that a suitably indemnified engineer is involved with the design, construction and supervision of any soakaway.

Septic Tank Upgrade Options

non electric sewage treatment plant

So you have a failing septic tank. You are having to get your septic tank pumped out and desludged regularly, especially during the winter months when the ground is wet. You want to know what your options are.

Septic tank problems are varied. And without expert advice, you may end up spending thousands only to have the same problem manifest again in a year or two. So our first bit of advice is to contact us now for professional advice! Below are a few typical problems with typical solutions.

Failing soakaway/percolation area

Your percolation area may have been installed poorly and may need to be reinstalled. However, in order to remove the risk of installer error, we would always recommend that you install a Biocell packaged tertiary treatment system instead of a percolation area. It will save you money, and they are independently certified units so they are guaranteed to work.

Leaking concrete tank

Many of the small precast companies that make and sell septic tanks do not complete water tightness tests of their tanks, so they are leaking before they are ever installed. Also, as all concrete tanks are in 2 parts – if the sealant is not put on properly [and it rarely is!] you will have ground water entering your tank. Extra water from the ground entering your tank means the sewage does not have enough time to be treated in the tank, which means low quality effluent and percolation area/soakaway failure. The only solution here is to replace the tank. The safest solution is a single piece roto moulded high density plastic tank. Guaranteed to be 100% watertight.

Damaged tank

If the tank is damaged and leaking – there is unfortunately only one solution. replace it!

Domestic Sewage Treatment Options

domestic wastewater treatment plant

There are many options for domestic wastewater treatment available on the market today.

Septic Tank Option with Percolation Area

Up until recently, a septic tank was the most common option. However, this is a passive method of sewage treatment with limited treatment efficiency. Now, stricter rules and regulations require better, cleaner  results. Thankfully, there are now plenty of better sewage treatment options.

A septic tank is basically just a settlement tank where solids are pumped out periodically. There is limited biological treatment so the quality of the discharge is very poor. This is why a percolation area or similar treatment option is specified. A percolation area is located in the ground near the septic tank and contains pipes, trenches and filters to process the wastewater discharge. A filterpod tertiary treatment module removes the need the for a large percolation area or soakaway by carrying out the same function in a tank based system.

Sewage Treatment Plant Option

In a lot of situations, current EPA and Environment Agency regulations will not permit the installation of a septic tank and will specify the option of a domestic wastewater treatment plant instead. By installing a modern sewage treatment plant you can discharge the treated effluent directly into a drain or watercourse. This removes the need for an expensive percolation area or soakaway. 

Modern packaged sewage treatment plants operate on the principal of mixing air with the wastewater. Bacteria then develop naturally and grow in the system. They feed on the organic material in the sewage and the oxygen introduced via the aeration process.

Low Energy Sewage Treatment Options

Many old fashioned systems have air pumps running 24 hours a day mixing air with the wastewater as part of the treatment process. Biocell low energy sewage treatment plants have the lowest running costs on the market. This has been independently verified by extended test periods. If you compare our EN12566-3 certification with any competitor model you can confirm it. Our systems are British water approved and SR66 approved for use in Ireland.

Our ground breaking electricity free system called the ClearFox Nature is the only non electric sewage treatment plant on the market that has no mechanical components, so it never requires replacement parts. This is a zero energy, low cost domestic sewage treatment option. Other competing non electric systems still require replacement parts and maintenance.

Septic Tank Upgrade Option

If you need a septic tank upgrade, then the ClearFox Nature or the QuickOne+ can be installed after an existing septic tank where the existing tank is used for primary treatment (settlement) of the domestic sewage.

Alternatively, if you are building a new house and require a new septic system, we offer the most robust, reliable and cost effective sewage treatment options on the market. Our experts are available to speak to you and give you advice on how to upgrade your septic tank or how to install a sewage treatment plant as part of your new build project.

SR66 Certified Small Wastewater Treatment Plants Ireland

domestic wastewater treatment plant

What is SR66?

SR66 is the standard that must be met by a small waste water treatment plant or product to be used in Ireland. The small wastewater treatment plant/product in question must already have met the relevant EN12566 standard.

SR66 references and expands on the European Standards and the Environmental Protection Agency Code of Practice relating to the selection, installation and use of small wastewater treatment systems in Ireland.

How can I check SR66 certification?

PIA GmbH is a testing body for the certification of wastewater treatment products. Together with the Irish Department of Housing, Planning Community and Local Government they have developed a list of products in compliance with SR66. Alternatively, if there is a particular domestic sewage treatment plant you are interested in, simply request a copy of the certificate from the manufacturer or supplier.

SR66 Certificate for QuickOne+

SR66 Certified Small Wastewater Treatment Plants by Biocell

All Biocell domestic and commercial wastewater treatment plants up to 50 P.E for use in Ireland are SR66 certified and therefore EN12566 certified.  More specifically,

Biocell QuickOne+

Biocell Concrete+

Additional Approvals and Certificates

In addition to SR66 certification, Biocell small wastewater treatment systems are also:

What requirements are covered by SR66 

SR66 certification ensures that a small wastewater treatment system is suitable for use in Ireland and that it meets all the necessary performance requirements. It includes additional requirements not listed by the appropriate EN12566 standard including those related to sludge capacity and scaling. It does not, however, cover the requirements for tertiary wastewater treatment systems. According to the CoP,

Tertiary treatment systems, which form part of
systems covered under I.S. EN 12566-3:2005
and prEN 12566-7, should conform to the
requirements of those standards.

EPA CoP WWTS Single Houses Pt.1

Difference between a Septic Tank and Sewage Treatment Plant

septic tank upgrade

In this blog, we discuss the difference between a septic tank and sewage treatment plant and explain which is better at treating wastewater and why.

In a nutshell, there really is no contest between the two. A sewage treatment plant does much more than a septic tank, but the terms are often confused and used interchangeably. Strictly speaking, a septic tank is not a sewage treatment plant but it can be used as part of a sewage treatment plant or system.

The primary reason you purchase a sewage treatment plant or septic tank is to receive and treat the sewage and wastewater from your dwelling. A septic tank is basically just an empty tank to store sludge. The only form of treatment that occurs is basic settlement of large solids.

Why is a sewage treatment plant better than a septic tank?

A sewage treatment plant is better than a septic tank because it actively treats the incoming sewage by aerating [adding oxygen to] the wastewater, either by a small air blower, or naturally via ventilation. The extra oxygen accelerates the natural biological process of breaking down the waste in the sewage.

Inside a septic tank, heavy solids settle at the bottom to form sludge. The rest of the sewage discharges into to the environment. So a septic tank has a treatment efficiency of approx 25%. In contrast, our best selling sewage treatment plant, the Biocell Quickone+, has a treatment efficiency of almost 99%. Big difference. Low quality septic tank effluent means pollution of groundwater, pollution of streams and clogging of soakaways with effluent with very high amounts of suspended solids.

So to protect the environment, to protect your drinking water and to keep your soakaway working well – a sewage treatment plant is a must have. If you have a septic tank and need to change it into a sewage treatment plant, have a look at our blog post on septic tank conversion and upgrade.

Can a septic tank be turned into a sewage treatment plant?

A septic tank can form the basis of a sewage treatment plant by acting as the chamber which facilitates primary treatment [settlement of solids]. After primary treatment, the effluent must flow to a second chamber for aeration, also known as secondary treatment [or biological treatment] to be considered a sewage treatment plant. The aeration process is what makes a sewage treatment plant different from a septic tank.

Tertiary Treatment for Domestic Sewage Systems

tertiary filterpod sewage treatment

See our more recent blog post on tertiary treatment modules for a more in depth guide and comparison of popular tertiary treatment units on the market today.

Many architects and engineers are now specifying a sewage treatment plant followed by a tertiary treatment module in place of a large percolation area.

Popular tertiary treatment systems on the market today include the following;

Sand Filters

Sand filters are very effective for tertiary treatment. They are layers of certified silica sands and gravels installed to EPA designs. Limitations of sand filters are that they can be large, expensive to install and require a certain degree of skill by the installer.

Coconut filters

There are some new tertiary treatment products on the market now that use waste organic material like peanut shells and coconut shell fragments to treat wastewater. These systems come in a tank preinstalled. The advantage versus a sand filter is that they are tank based systems so they are simple to install. A disadvantage is that they are expensive in terms of cost price and maintenance.

Filterpod Units

Biocell offers filterpods for tertiary treatment. Certified to EN12566-3 and EN12566-7.  The systems are ready to go and come preinstalled in a small tank. Additionally, the filterpod can be used in place of a percolation area. The filter media is synthetic – and costs far less to replace than organic waste material. Far better value and easier to install than sand filters.

Septic tank bacteria myths exposed

e coli bacteria

Does adding septic tank bacteria improve performance or solve problems?

The short answer is no. Adding bacteria to a septic tank system is pointless. A septic tank system is an anoxic settlement tank [low levels of oxygen]. Bacteria need oxygen and food to survive and flourish. Adding bacteria to a tank with minimal oxygen levels means the bacteria will perish rapidly and will achieve nothing. 

Not only that, but the bacteria population inside a sewage system is limited by the food available [i.e. the incoming sewage]. So adding bacteria to a tank that already has the maximum population of bacteria present has no positive impact.

How long does it take for septic tank bacteria to develop?

We are often asked if our sewage treatment plants need bacteria to be added to them to work properly.  With an aerated sewage treatment plant, within the space of 2-3 days after startup, a full colony of naturally occurring bacteria will have developed in the system. 

To summarise, if you have just installed a new sewage treatment plant, our advice is this – do not purchase septic tank bacteria, save your money! The bacteria will develop naturally within 2-3 days of the system being up and running. 

Additionally, if you have an old or faulty septic tank, adding septic tank bacteria will achieve nothing. Have it looked at by an industry professional instead and it will be money well spent.

On a final note, bear in mind that the majority of companies that supply septic tank bacteria products offer no guarantee or independent certification for these products.