Sewage Treatment Plant Selection - Which Sewage Plant Is The BEST?

Comparision of EN12566-3 Test Results

Below is a comparison list of Performance Results during the EN12566-3 Test -  Taken from the EN12566-3 PIA Test Centre website.

The figures are the average of the 38 weeks testing - the lower the figures, the better the result. It is probably better to avoid plants which have figures in red that are at, or close to, the limits, as they must have exceeded the limits on some test occasions and you are not allowed to exceed the limits at all.

Make of PlantBiological Oxygen Demand (BOD) Mg/LSuspended Solids {SS) Mg/LAmmoniacal Nitrogen (NH4 - N) Mg/L
Environment Agency Maximum Limits203020
Klargester Biodisc20235
Klargester Envirosafe12213.4
Klargester Bio-Ficient20270.4
WPL Diamond10217.3
Balmoral Hydroclear11194.5
Tricel11168
Graf Klaro E122012
Condor ASP8127.7
Falcon11165.9
Vortex7.315.20.4
FilterPod Non-Electric101211
Premier Tech Aqua Ltd. Epurfix Non-Electric111420
Clearfox Non-Electric92912

BUYER BEWARE!!!!

  • Some manufacturers that have got the EN 12566-3 2005 but which have failed the above reductions do not offer the Certificate and refuse to send a copy when asked. Others claim that their plants are 'Designed to' or 'Conform to' the EN 12566-3 standard. This is like saying that you are educated to 'A' level standard - it does NOT mean that you passed any! Some still refer to the outdated BS 6297 1983 or ISO 9001 and hope that you don't know the new regulations. Some even only offer the letter from the EN Test Centre confirming delivery of the tank for testing (written in German or French to confuse the issue). These have presumably failed E.A. criteria on the test.
  • Some manufacturers only had their plants tested for the effluent from 4 persons during the test, but sell the plant as a 6 person. Ask how many litres/day the plant received during the EN Test - it should be 1.200M3/day for a 6 person system, not 0.6M3/day, as with some plants.Some manufacturers have the EN test done with too little organic material (BOD) for the number of people they are testing for. In the UK, each person produces 60gms of BOD/Day, so for a 6 person plant, it needs to be tested with 360gms BOD/Day, for a realistic test. Some 6 person plants have only been tested with 230gms/day. It is a cheating world, unfortunately.
  • Many manufacturers choose to test their plants for 38 weeks during the warmer months, missing out December, January and February, in order to get better EN Test results. This is because bacteria don't work very well in cold temperatures. However, it is not really a fair test as your plant has to work during the winter as well. If the plant has been tested this way, then the average test results are biased.
  • Some manufacturers claim extended emptying intervals that are not really honest. The wording of the claim is very clever, e.g. "Up to 5 year emptying intervals" - yes, if there was only 1 person living in the house and they were out at work all day! You need to ask how often it will need emptying if fully loaded and even then, you may not get an honest answer. Assume that ALL package (all-in-one tank) plants need emptying at least annually under normal use. For more information visit Why we think that the EN 12566-3 is a flawed test.
  • Some manufacturers opt out of the EN12566-3 Wet Pit Test which is optional. If the tank has not had this test, then you have no idea how it will cope with high groundwater. Make sure that it has the Wet Pit Certificate if your site has a high winter water table.

Cheap sewage treatment plants may not be the most economical option, as running and installation costs vary enormously between different types of wastewater equipment, depending on how each one works. Some are probably not even legal. If you want a low cost system that WORKS and is certified, consider the VORTEX™ sewage treatment plant from £1550 plus VAT. Click here for How the Vortex sewage system has such low energy consumption.

WTE Ltd. technical staff can help you with your sewage treatment options.

Which Type of Sewage Treatment System is Right for You

Choosing a sewage treatment system manufacturer can be a nightmare as there are so many on the market that you probably have no idea how to choose the right one for you? The most important factor is that the manufacturers plant has an EN 12566-3 2005 Certificate as without it, it is no longer acceptable in the UK.

For flood plain sites, there is only one option for wastewater treatment.

There are 3 different types of domestic sewage treatment plants,plus the new non-electric FilterPod sewage treatment plant.

Differences between the sewage treatment plants available

 
Sewage Treatment Plant

Vortex small image

FilterPod non-electric sewage treatment plant

Electricity requiredYES (not very much)Yes (from £25/year - VORTEX) NO
Emptying Interval
3 to 18 months
1 year1 to 2 years
Smelly Primary Tank
SOME (Unless Vented)
NONO (Vented)
Internal Moving Parts
SOME (Disc plants)
NONO
Ability to perform during intermittent use (holiday lets, etc)SOMESOMEYES
Ability to perform if underloadedYESSOMEYES
Visually Intrusive
SOME
SOMENO
Expensive Servicing
SOME
NONO
Warranty Period
1 to 25 years
5 to 10 Years10 years
Effluent StandardOK to ExcellentExcellentExcellent
Makes of PlantsTraditional 3 StageActivated SludgeNon-Electric Filter
 ValanceVORTEXFilterPod
 Falcon  
 Klargester Biodisc  
 Entec Biotec  

The new standard for private domestic sewage treatment plants in the UK is the BS EN 12566-3 2005 - not to be confused with CE marking which is not mandatory. Trading Standards and the Environment Agency have advised us that only plants which already have this BS EN 12566-3 2005 test conformity certificate are legal for sale in the UK, as it is now a requirement under the Environment Agency General and Binding Rules.  Many plants, including some of the manufacturers above, do not have it, or the plant performed so badly in the test that they do not declare it. These plants do not conform to Trading Standards or Environment Agency requirements. Before you decide on a wastewater plant, DEMAND to see the independent TEST REPORT, NOT the CERTIFICATE, and do not be surprised if they are refused!  If they are refused, DON'T BUY IT! See also Wastewater Legislation.

Questions to ask the sewage treatment plant manufacturers

Does it require electricity?

All plants apart from the FilterPod require electricity to work. Some need much more than others! Make sure you ask what the average KW hours/year the plant uses BEFORE you buy it! This is particularly important for the larger sewage treatment plants as the cost for a 100 person plant can be £12,000/year, depending on how it works.

How often should the sewage treatment plant be emptied?

Emptying is often the most expensive part of system running costs. Emptying intervals also depend on how it works. All of the 3 stage package plants need emptying every 3 to 12 months, depending on the size and make of the plant, as they don't fully digest the solids, but store them as sludge in the primary tank. The extended aeration sewage treatment plants partially digest the solids as well and have a 1 to 2 yearly emptying interval, depending on the model (not 5 years as is the claim with some). The FilterPod has a 1 to 3 year emptying interval.

Can I have a copy of the full EN12566-3 2005 test RESULTS?
 
BEWARE as many sewage treatment plants for sale in the UK have NEVER been tested by anyone!

Others, even some made by the leading names, which have passed the EN12566-3 2005 would NOT pass the UK Environment Agency standards which YOU have to adhere to!! This is because the EN12566-3 2005 only tests the percentage reduction of pollutants in the final effluent, NOT the final effluent quality produced by the sewage equipment! Yes, it is stupid as many sewage treatment plants which failed, during the test, to meet the UK Royal Commission Standard of 20BOD:30S.S.:20NH3 on a 95 percentile basis have been given the EN Certification! This is why many manufacturers will only offer the Test Conformity Certificate and not the test report!

If they WON'T give you the Test Report, DON't buy the plant!

It is YOU that the Environment Agency prosecutes ( see Latest News) not the sewage equipment manufacturer!
 
Does it have a Primary Settlement Tank?
 
If it does, then it is a 3 stage wastewater treatment plant as described above. Unvented UK Primary Settlement Tanks do not tend to be odourless as gases can escape through the sewage treatment unit lid, particularly when the bath, etc. is emptied, displacing air through the lid of the plant. It is called Primary Settlement Tank Odour. Ask if the PST is vented as part of the works!
 
Does it rely on internal moving parts?
 
Moving parts wear out and sewage is very corrosive.  Replacement parts - motors, gearboxes, bearings, drive shafts, pumps, etc.- and labour can be very expensive for some plants.
 
How thick is the fibreglass/polyethylene?
 
This can vary between plants from about 3mm to 10mm, depending on the make of unit. Obviously, the thicker the better as thin-walled tanks can distort or crack under the pressure of groundwater or soil on the top.  In this business you really do get what you pay for. A sewage plant is only as good as the tank it is made in. Click here for why the sewage treatment plant tank quality is important.

Does it need an additional sampling chamber?

Most sewage treatment plants require a sampling chamber after the sewage plant. Some, like the Vortex, do not. As this chamber costs around £250 plus installation, it can add considerably to the total cost of the wastewater treatment system.
 
What do you see when the sewage treatment works is installed?

Some plants are an eyesore, either because the lids are enormous and protrude well above ground level, or because there are multiple large lids on view.  Some sewage treatment units have large, unsightly Kiosks containing compressors and timers etc. whilst others are small and inconspicuous.

How clean is the effluent?

Sewage treatment plant vary enormously in their ability to treat sewage. The majority only treat it to a minimum standard to satisfy Environment Agency requirements, but some treat it to a far higher standard and provide a safety net when relatives stay. Again, you get what you pay for. Compare the table at the top of this page.

How much is the annual servicing cost?

Servicing costs for sewage equipment also varies enormously, from £75.00 to over £300.00 per service, depending the complexity of the unit. All extended aeration plants require 2 services per year, not one. A general rule is, the simpler the treatment system works, the cheaper the service. Ask what the service cost is per annum.

How long is the tank warranty?

This varies from 1 year to 20 years, depending on the plant manufacturer. Ask about the warranty period as, in our opinion, 12 months is far too short a warranty for a tank costing upwards of £2000.

In our experience, tanks do not tend to crack during the first 12 months. They crack as the pressure increases over time due to settlement of the ground around them. This normally takes place over 18 months to 2 years, so what use is a 12 month warranty? It is only of benefit to the manufacturer who does not have to replace the tank when it fails.

All sewage treatment plants that have the EN 12566-3 Certificate, except for the Klargester Sigma (now called Entec SuperSeptic), should be suitable for direct discharge to a ditch or watercourse, subject to Environment Agency Permit to discharge. However, not all sewage equipment is designed for this type of disposal system. Septic Tanks are NOT, and expensive soakaways, with a limited lifespan, must be constructed to dispose of all septic tank effluent.

WTE gives INDEPENDENT advice on all the above sewage treatment manufacturers and equipment