Water softener waste problemette............

[Ian Middleton]

A mate of mine has had a whole house water softener fitted in a cupboard next to the sink and all works fine as far as soft water is concerned.

Anyway there is a salt tank overflow pipe in case the tank continues to fill, that allows the excess water to drain away. The plumber has routed the overflow pipe (16mm clear plastic ?) to the cupboard next door and through a hole in the "bung" (also containing the 40mm sink/dishwasher waste pipe) in a 4inch waste pipe in the concrete floor. There is a trap underground.

This appears a nice neat solution, but when the sink/dishwasher empties smelly air from the drain (above the trap) is forced out of the water softener overflow pipe and makes the cupboard stink. He has clamped off the overflow pipe and smell has stopped.

He can't route the pipe outside as there is no outside wall convenient, basically a conservatory is in the way to the nearest outside wall.

Any thoughts ? Are there one way valves that will let water out but not let air in ?

Can't really use a trap as there is no flow normally and would probably dry out and let gas through again.

[Lee]

A Hepvo might work, but you'd need to cobble together some sort of adapter from standard fittings and it may not look very neat.

Lee

[Andy Hall]

The softener will also have a waste water outlet as well as the overflow. If both are routed to a trap then the problem is solved because there will be regular flow of water into it.

[Ian Middleton]

Looks just like what is needed and from what I can remember I think there is sufficient space under the sink to fit the Hepvo onto the existing pipework.

[Ian Middleton]

I don't think this can be done with the existing waste pipework as there is a washing machine trap with associated "riser pipe" also connected. The water softener waste feeds into the "riser pipe" of the washing machine trap via a 45' junction. The softener overflow cannot go higher than the softener, thus if an extra trap was added there might be a chance of the washing machine or sink flowing backup the softener trap and overflowing.

I think the Hepvo solution is the most likely solution.

[Andy Hall]

I see the issue now.

If you do go the Hepvo route, I would test it very carefully.

The seal opens under pressure from water in an appliance (i.e. basin) being applied to it.

doesn't say what that pressure needs to be.

Bear in mind that you are talking about a small overflow pipe and from the description of the layout, very little head.

[Rod Hewitt]

Andy Hall wrote in news: [e-mail]:

If fitted vertically, there is effectively never any water in the trap - I am sure that even a single drop would make its way through. IMHO "pressure" is only required to open it wide enough for significant flow. When pruchasing one, I got ribald comments in some merchants as they likened the HepVO to condoms - though I would have to say that the membrane is certainly thicker than any with which I am familiar.

[Ian Middleton]

My mate called the plumber back and he agreed there was a problem, thought about it for a while and did the following.

Using 21mm (?) overflow pipe he has made a U-bend trap, out of 4 right angles, all solvent welded, and fed the outlet of this to the drain via the bung. The input to this is from both the softener waste water and overflow. The two input pipes are siliconed on via some compression fitting allowing it removed.

All this is at low level, on the concrete floor so the water overflow has a drop into the "trap". As the softener waste is only 1l/min this appears to be able to cope easily.

So far no sign of waste water (or main sink/washing machine waste) going back up the softner overflow pipe so looks like its working, and no drain smell reported.