what is this thing in my garden?

[resybaby]

Dont go sticking anything longer down the valve and rattling it about. If you break the valve you will soon find out what it is as your garden gains a huge fountain and you wait for the water company to come to fix it. 2.5" of water at mains pressure churning up a garden makes a nice mess.

Get the records from the local water company, you can inspect for free in an office and most will have some form of online access portal.
Whatever you do DO NOT dig it out, if its an inline valve (which will be on a branch/stool piece) it wont matter. But if its an end fire hydrant (or wash out, they are identical) it could get blown off the end of the main and you will enjoy the provision of a nice new garden river. I have seen this done many times.

The water company maps will not show this item if it is a air release/bleed valve like i mentioned earlier. They should show a FH or WO (identical other than the fire brigade technically pay to repair FH's and the water company pay for WO').

The installation isnt clear enough to make a 100% choice what this is, and i have 39 years experience of water company distribution networks, the threads look wrong for me to say FH or WO categorically. Normally there is just a single threaded end with a very course thread to fit 2.5" fire hydrant standpipes onto, yours looks like it has an extra bit of the end from normal, hence me thinking bleed/air release.

If you have a local fire station, could always ask them to pop out and try fitting one of thier standpipes to it, they are likely to be more helpful than a water company.

[resybaby]

of course if your very rural, which it appears now memtioning land drainage, then it could be some old left over farmer private irrigation installation, in which case the best of british finding details out - although that would explain the odd end fitting i refer to before.

If you open the square ended valve SLOWLY with an appropriate spanner, opening slowly and turning back to closed as you proceed, you will find out if its live as water will 'seep' up the outlet end - only issue would be washing some of that mud into the water mains, if indeed thats what its connected too.

The Ecoli/contamination issues recently in Exmouth or Brixham (i think) was 100% down to an exact situation with a submerged (in mud like yours) air release valve in a farm field letting mud back into the main. Cost the company millions in compensation and set off a manhunt looking for the same very very common problem on mikes and miles of pipes in private land.

[resybaby]

Apols it was crypto in the water not ecoli

https://www.southwestwater.co.uk/about- ... in-brixham

The "damaged asset" the article refers to was a faulty air release bottle valve in a farmers field that was (stupidly) buried below ground in a chamber that intermittantly jammed 'open' letting cattle waste and mud seep back into the supply.

Common to see such equipment out there, but proper practice to keep such installations to edges of fields (farmers love removing above ground obstructing chambers in middles of fields) and never install below ground. Quite often a manually operated standard stoptap needing human action to operate is used - adds a semblance of better risk management.

[AE-NMidlands]

If you open the square ended valve SLOWLY with an appropriate spanner, opening slowly and turning back to closed as you proceed

I was on a night job once when the mains water supply to a city-centre site which used to need a BIG mains connection had to be turned off... instead the valve snapped off in the road and created a big river down the gutter. It was quite fun to see the water company turn out and deal with it as just one of those things!
"It all makes work for the working man to do!" If you are too young to recognise the quote, Google it!

[Oliver90owner]

My first thought might be “Which side of the water meter is it?”