Shower waste, no return valve

Have got three HepVO "traps". No problem with any of them over something like seven or eight years. Indeed a plunger might not be very effective with them - but the only issue we have had is long hair in bathroom basin. So make sure it is accessible - only takes a couple of minutes to unscrew, push/flush, re-fit.

Our bathroom basin one is vertical, directly under the waste, then the pipe goes round the room before flowing into other waste pipe. That was the only way it would fit and be fully accessible.

Our downstairs basin one is horizontal. But that can still be unscrewed easily.

The other one is on the bath. Horizontal. And would be a pain to unscrew

- but possible.

They would always be on my list in the future though final choice would depend on circumstances.

Why do you believe you need a NRV?

What would it achieve?

If you discharge a basin-full of water and have the taps running full- rate into the basin then if your pipework is arranged properly it should be able to take the water away to the drains without backing up to the shower waste and causing bubbling up through its trap. If it can't do that you've got your waste run wrong and an NRV is a bodge to get around it!

If there's a blockage downstream of the join between shower and basin wastes then an NRV will prevent the basin's waste backing up into the shower, but if you run the shower it'll fill up and overflow anyway, so no gain there!

(Just my 2e-2ukp-'orth)

Because I can easily fit one now but will find it difficult once the shower tray is nailed down.

I have only the bare 18mm/m fall and the shower has only 25mm of water trap.

Noted:-)

I'm not seeing any need either.

NT