Not to forget the hidden risks when selecting septic tanks. British Water's Sewage Treatment Plant Focus Group has warned that the industry is in danger of ignoring the pitfalls of using septic tanks instead of proper packaged treatment systems. Treatment plants operate typically at 90% efficiency and septic tanks rely on the suitability of downstream percolation in the ground to achieve maybe 50% efficiency. When partly treated septic tank effluent enters the water table it effectively pollutes groundwater. That takes years to repair.
EN12566 which insists that sewage treatment plants are watertight, corrosion resistant, structurally durable and fitted with an alarm, means that European-wide standards have been adopted here. This opens up the European market to UK producers and the UK market to European competitors.
But Mike Norton, chair of the British Water Sewage Treatment Plant Focus Group, which has published a code of practice for sizing STPs called Flows and Loads ( free to download from www.britishwater.co.uk), has expressed concern that septic tanks will not be as rigorously checked as the treatment plants.
"Septic tanks rely on the validity of assessment and use of the downstream soakaway to achieve any meaningful treatment. In the real world, this so often doesn't happen."
He also expressed concern that Part 1 of the standard covers septic tanks but fails to specify a pass mark for hydraulic testing.
The European Court has recently prosecuted the Irish Government over non compliant Septic tank discharges into groundwater.
"As a leader in raising standards in the waste industry," he added "the Focus Group at British Water needs to work with and offer help to the Trading Standards regulators to uphold the high standards we've fought for over the past many years"