The really insidious thing about septic tanks, is that they give the general public the message that we care for the environment, when in fact as much pollution passes through modern septic tanks as would come from the disposal of raw sewage.

In the fifties and sixties, when I served my apprenticship,all septic tanks worked well, passing clear odourless water to the outfall.....It is at least thirty years since I have seen a septic tank which is performing its proper function.
The old septic tanks never needed emptying....the bacteria took care of all the solids. I have seen tanks which had never been touched for forty years and were still working perfectly.

I have taken this matter up with planning and building control in the West of Scotland on numerous occasions and they are aware of the problem, but rely on frequent emptying....as GSG says the effluent is then pumped into the sea at some convenient point
and the pollution continues.

Less developement means less pollution.