"Eddy Bentley" wrote in message
We have a reasonably-sized septic tank embedded in the front garden and
we understand that the previous owner had it cleaned every year, at a
cost of about £120. There has been a suggestion that this annual
cleaning is a bit excessive. On the other hand, I have read that if the
solids mount up and leave the tank and move into the soakaway area then
the soakaway area becomes clogged and you then have to build a new
septic tank at another (clean) spot - which is a real bother and a
considerable expense. So, clearly, regular cleaning is worthwhile.

But how often is regular for a two-person household?

That price for emptying sound very high (but then I'm not in the UK).

Emptying depends on a few things. If it is the older style tank without the
new fangled electrical connections for pumping onto gardens etc, and if the
installation has been done in more recent years by someone who is in any way
competent and the tank is of a good capacity, it 'should' be able to go a
lot longer than being emptied ever year.

We are 2 people in a 2 septic tank household (one septic of which gets
little use - just the visitor's bathing and flushing) and the last time we
got ours emptied (after being in this house and not emptying either for 10
years) the pumper outerer said to have them done at 5 year intervals. That
would now be more than 5 years ago and we can probaly go at least another 5
years before doing anything. Our tanks would probably be about 2,000 gallon
capacity if I compare then to water tank size.