European Standard EN12566/3 is a rigorous test for small treatment plants (for treatment plants up to 50 population) assessing their efficiency. It is a test performed on all products sold as a “packaged treatment plant”.
The test takes 37 weeks and tries to mimic the real life working of a treatment plant and how it performs under low, normal and high flow. It also tests the structural integrity of the tank. The results of the water quality are expressed in BOD5, ammonia and suspended solids. The lower the number equals better quality of treatment. This is more of a type test, rather than a pass or fail. A treatment plant can still get an EN certificate even if it performs poorly or has to be de-sludged frequently during the test. The certificate is therefore a good place to get an indication of a treatment plant’s performance, but should not be your sole consideration when choosing a treatment plant.