On 16/08/2018 16:55, NY wrote:
"Nightjar" wrote in message
...
....
There is absolutely no requirement to modify existing plants. All
existing plants, no matter how old, can be left exactly as built. The
requirement is that you must ensure that the outflow from the plant
does not contaminate a waterway.

Which may amount to the same: you may need either to modify your plant
so its output is cleaner, if it discharges into a waterway, or else you
may need to modify where the unmodified outflow goes (soakway rather
than waterway). One way or the other you may need to pay, even though
your system met the relevant standards when it was installed.

The result may well be that you need to spend money to clean up the
outfall, but that does not constitute a retrospective application of
current standards to the plant itself.

The OPs plant and drainage filed will not be certified to the relevant
British Standards. However, neither needs to be changed in any way to
meet the regulations. If the General Binding Rules required the septic
tank to be replaced with one certified to BS EN 12566-1 and the drainage
field to be replaced with one designed and constructed to BS 6297:2007,
that would constitute a retrospective application of standards, but they
don't.

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Colin Bignell