2ndry water meter on garden tap

Look up 'sub-meters'. eg SWW:

You may benefit from having an external-use or sub-meter if you use a large amount of water externally, for example:

A very large garden that you water by hosepipe or sprinkler for more than 15 minutes each day A garden pond larger than 1 cubic metre or 220 gallons in capacity that you regularly fill or top up A swimming pool that you regularly fill or top up, that doesn’t drain into the main sewers An automatic garden irrigation system which is used daily for more than 15 minutes

To get one fitted by South West Water, the cost is £154.00 plus VAT and any other plumber charges for adjustments to pipework, if required.

Alternatively, following assessment for suitability, we can provide the meter manifold to be fitted by yourself or a private contractor. Once this is done, we would attend to install the meter into the manifold. We would not charge for this service.

Contact us today for more details. </quote>

I couldn't immediately find the equivalent for Southern Water, but you can ask them whether they will provide a suitable meter or if they insist on a particular type.

Theo

I had an external water meter fitted for just this purpose 6 years ago. I'm also in the Southern Water area. You will find nothing on the Southern Water website about it, as it's a nice little earner for them. Officially, they call it "non-return to sewer allowance".

When I spoke to them about having a garden meter fitted they were insistent about having a plumber do it. As I wanted it done quickly, I contacted my plumber and he said he could fit an Altecnic GG-3003F13 water meter. They also fitted two new outside taps to replace the ones already there as they did not have non-return valves (one in the back garden and one in the front garden. Only the back one has a meter, as I rarely use the front tap). The work for the garden meter was fairly straightforward, if a little awkward, and also involved moving the tap to a higher position. When it was all finished I fitted a wooden box around the meter for insulation, as they aren't usually found outside in an exposed position and possibly subject to frost.

The meter paid for itself within two years. One nuisance is that Southern Water have no system for including the garden meter reading in their bills. I get an emailed bill for /all/ the water used, then I have to ring them up and give the garden meter reading, which is then sent to their Accounts team, and a few days later they send me a new bill with the meter reading subtracted.

Since I had the meter fitted, I've saved the sewerage charge on over 147m^3.