Do i need a non return valve on my outside tap for a pressure washer?

Hi, this is probably a stupid question, but do i need a non return valve on my outside tap for a pressure washer?

I have ordered a Nilfisk core 150 pressure washer, and before it comes i thought I'd download the manual and have a look.

It's all just diagrams, but shows that a non return valve should be fitted between the tap and hose, and shows a house fitted directly to the tap with a cross through it.

From what i have read, this may not be relevant to the UK, especially newer outside taps as they now have this built in by law. Is that correct?

My house was built 6 years ago, so thinking of might be ok, I'm not sure how i know by looking at the tap if it has a NRV?

I used a pressure washer on the same tap before without issue, i don't think there was any mention of needing a NRV with that one. This one's more powerful though, so just wanted to make sure and be careful i don't damage anything.

Any advice would be great.

Regards
James

 

Yes - it's a requirement that all outside taps must have a NRV
I didn't have one for years, but when it eventually needed replacement I had one with a NRV

• Legal requirement:
  Water regulations in the UK require double check valves on all outside taps to prevent backflow and ensure water safety.

 

Brill, so i am safe just ignoring that part of the manual, and fine to connect directly?

 

Maybe - but I don't know if your tap has an NRV or not..
Mine has, but there's no obvious way of telling it has, but yours 'should have' one if it was 6 yrs.
Mine was replaced in 2019

A plumber had a water pressure meter and tired it on my outside tap and the needle went off the scale and broke the meter.. so that's one way of finding out

 

It's a requirement under the water byelaws to prevent backlog protection to prevent contamination

 

I think @shiney is probably correct. Certainly nothing on the 1 outside tap I have here. On the rare occasions I need to make use of it, I simply stick a bit of hose pipe directly on to it and fill a watering can. Altho this house dates back a couple of centuries, the main foundations are much older. The tap is situated on an extension which was built in the 1970's. Never had/used a Pressure Washer so unaware of any possible problems.
Water pressure can vary tho so may be better safe than sorry ?

 

I replaced my outside tap few years ago as it was dripping, just bought a new one at wickes, they seem to mostly come with it in the tap these days.

It's nothing to do with pressure washers it's to do with stopping back flow from your hose to the mains should the water get cut off.

I often fill my water butts with the hose and just shove the hose in the butt, when full the end of the hose is often under water, if the water got cut off the water butt could siphon water into the mains without the valve.

 

I have a non-return valve screwed on to my outside tap, that I bought when I found out that you were supposed to have one. Our house was built in around 1950 and the outside tap had been installed by the time we bought the place in 1988 so I the tap probably didn't have the valve built in. And if it does, no harm done having an extra one.

 

Hi, just so people can see. This is my outside tap and inside pics below.

The other pic shows whats right behind it, on the other side of the wall.
It comes inside and where I have circled orange, it's that pipe and also has an isolation screw and then connects to the boiler.

The part where in goes into the boiler are also the yellow circled nobs I would use to refill the boiler if the pressure goes down.

Not sure if any of that makes any more sense to the setup my tap is using?

 

I wouldn't like to say if you tap has a non return valve, my tap looks very similar and it does, but then again it looks very similar to the one I replaced which didn't have one.
I don't think what goes on behind the tap has any bearing on the matter.

https://www.screwfix.com/p/essentials-outside-tap-with-double-check-valve-15mm-x-1-2-/37241

 

The orange thing is just a normal bolo fix for switching flow off, and I don't see any valves near those blue handles. I have a house built in 2014 and the tap looks similar, but mine has something engraved on it. If you can photos of that and Google it, it might indicate whether there's an internal non-return valve.
You can buy the plastic units that include one pretty cheaply, so I'd just add it to your tap if you're worried.

 

If it as a bobble or small nut it as a non return valve like mine which as .underneath

 

You can buy a non-return valve that screws on to the tap (where the push-fit attachment is), then the push-fit screws on to the other end of the valve.

This sort of thing https://www.screwfix.com/p/flomasta-double-check-valve-dzr-22mm/26003 but check whether you need a 22mm or a 15mm one.