"The Natural Philosopher" wrote in message
news
The regulation says that by 2020 or if you sell the house you must modify
your private sewage plant to meet a given standard.

How severe is the standard? How many two-chamber septic tanks installed
(say) in the 1960s and 70s would pass? If not, what sort of modification
would typically be necessary to make it comply (in terms of cost and
disruption during construction)?

Is it similar to the new rules about MOTs and diesel emissions, where there
was a lot of scaremongering in advance, but in practice the vast majority of
cars still pass and it is only ones with a damaged or removed diesel
particulate filter that would fail.