Water Softener Plumbing - two pipes or one?

[puntloos]

The softener I picked (somewhat arbitrarily I admit) is the Monarch Midi HE - https://www.bathquest.co.uk/Monarch-Midi-HE  (manual)

 

In the manual it says: "Under no circumstances should the softener drain and overflow share the same pipe. This could lead to foul smells entering the salt cabinet from the main drain via the overflow. Also if the common drain ever gets blocked, the regen water can re-enter the softener via the overflow pipe."

 

And, in my house this is how the plumber has done it:

 

So.. yeah. My questions:

 

1/ How can 'smells' can really come in, let alone affect the water? And importantly, can we not install eg a one-way valve on this drain to avoid such smells?

2/ It doesn't sound _great_ that regen water comes into the softened water, but presumably that's just brine water, so while uh, drinking super salt water in that eventuality is not ideal it sounds like a one off...

3/ The drain they installed, ok it is one pipe, but even if you would make two pipes, surely at some point those have to come together into the same drain? Or are they expecting me to route the two pipes to different drains somehow? Doesn't sound realistic..

 

Basically, I don't want to be too difficult to my plumber, but just want to figure out how to handle this. 

[Kelvin]

My overflow wasn’t even connected. Ask me how I know. 
 

It doesn’t mean two separate drains it just means two separate connections (like your dishwasher and washing machine) My softener and nitrite treatment overflows via a pipe into the dog bath. 

Edited November 27 by Kelvin

[G and J]

I believe the overflow should be visible, i.e. through a wall to outside or maybe to a tunndish thence a waterless trap. 
 

If it’s overflowing you will want to know. 
 

Others might be different but our softener has a reservoir just sitting there.  When regenerating that water mixes with supply water.  We don’t drink softened water but the idea that my washing or washing up water is partly stuff that’s sits with a direct connection to drains/sewers isn’t nice.  

[puntloos]

7 hours ago, Kelvin said:

My overflow wasn’t even connected. Ask me how I know. 
 

Ah that sounds like a fun story.. but ok, won't ask.

 

7 hours ago, Kelvin said:

It doesn’t mean two separate drains it just means two separate connections (like your dishwasher and washing machine) My softener and nitrite treatment overflows via a pipe into the dog bath. 

OK so the picture I showed is "too common", but having two pipes that at some point down the line join is better somehow? Sorry I'm not a plumber so I don't exactly know when there is 'sufficient separation'? Does that mean, for example, that the lines have to run at least - some distance (2m? 3?) by themselves, or the lines have to have a drop of something? (5cm? 10?) by themselves?

[puntloos]

8 hours ago, G and J said:

I believe the overflow should be visible, i.e. through a wall to outside or maybe to a tunndish thence a waterless trap. 
 

If it’s overflowing you will want to know. 
 

Well my current setup has made it visible, and it .. visibly overflowed.. once already. (due to pipe not dropping steep enough, fixed that now)

 

8 hours ago, G and J said:

Others might be different but our softener has a reservoir just sitting there.  When regenerating that water mixes with supply water.  We don’t drink softened water but the idea that my washing or washing up water is partly stuff that’s sits with a direct connection to drains/sewers isn’t nice.  

Are there official "separators" in plumbing? Types of one-way valves that will make sure that water can 'never' go up the wrong way?

This is a super newbie question but I imagine that just demanding to put 2 of those in the two lines of the softener will address most concerns?

[Kelvin]

The overflow  drain is typically taken outside through the wall to drain with suitable protection from freezing. If you can’t do that drain it into a bucket. The overflow will only be a problem if you have a failure. The most common failure is a blockage so the brine tank slowly fills up. It might take two or three brine regenerations before the water reaches the overflow. My tank has some scale marks on it to allow you to keep an eye on the water level in the tank. But it’s important you can see that the overflow has water running out of it (under gravity) 

Edited November 27 by Kelvin

[Oz07]

10 hours ago, G and J said:

I believe the overflow should be visible, i.e. through a wall to outside or maybe to a tunndish thence a waterless trap. 
 

If it’s overflowing you will want to know. 
 

Others might be different but our softener has a reservoir just sitting there.  When regenerating that water mixes with supply water.  We don’t drink softened water but the idea that my washing or washing up water is partly stuff that’s sits with a direct connection to drains/sewers isn’t nice.  

Surely it doesnt mean an untrapped drain connection?

[sharpener]

AIUI the regen flow to waste might be able to withstand some back pressure. There is a washing machine waste standpipe fitting which is designed as a clamp-on tee connection to an existing 50mm kitchen waste, and incorporates a non-return valve. That might work for the regen waste. Otherwise used a U-bend trap or take it to a trapped drain then there will be no smell.

 

The overflow by the sound of it will not tolerate any back pressure so should go out through the wall to a safe but visible overflow location e.g. above a porous surface or a surface water drain. IME the "Hotun" combined tundish and waterless trap is NBG, it requires quite some flow to open the valve (even though the spring is so light it does not shut the valve reliably) and overflows onto the floor at only slightly more flow.

 

Hep2O type of waterless bladder trap not much better, a lot of back pressure is required to open the bladder, to the extent it backs up to my UVC tundish.

 

 

Edited November 27 by sharpener

[G and J]

So if a tundish must be used then drain that to a standard u bend or similar that is also used by something else to ensure the trap never runs dry.  
 

My water softener will be in the garage outside my airtight envelope so through wall o/f looking good. My UVC (upstairs) tundish and fancoil drain however will drain to a trap (downstairs) which is also used by the kitchen sink.  

[Tommy M]

On 27/11/2024 at 06:55, Kelvin said:

My overflow wasn’t even connected. Ask me how I know. 
 

It doesn’t mean two separate drains it just means two separate connections (like your dishwasher and washing machine) My softener and nitrite treatment overflows via a pipe into the dog bath. 

My overflow wasn’t connected too. Geez

[G and J]

4 hours ago, Tommy M said:

My overflow wasn’t connected too. Geez

On the brightside, if you did have a problem at least you would know about it as your socks got wet through when you walk into the utility room.

[sharpener]

18 hours ago, G and J said:

On the brightside, if you did have a problem at least you would know about it as your socks got wet through when you walk into the utility room.

 

When my HP was fitted we discovered that the pressure relief valve on the oil boiler had been vented straight into the utility room for the last 29 years.

Previous owner had done a lot of the plumbing himself, filling "loop" was actually 15mm rigid pipe with only one valve as well but I knew about that.

[puntloos]

One thing I was thinking of is asking to install a one-way valve on these outputs? Would that solve some/most of this issue?

[joth]

21 hours ago, puntloos said:

One thing I was thinking of is asking to install a one-way valve on these outputs? Would that solve some/most of this issue?

You can't use a double check valve or similar as there's not guaranteed to be enough pressure in an overflow situation to open it. Drains normal stop back flow using gravity, that's essentially what the standpipe is for in your setup, and in a washing machine outlet, and the tundish mentioned above is essential the same idea. The problem is water softeners don't have much vertical drop hence the very crammed standpipe and risk of it filling up and syphoning back. Our softener is installed on a meter high pedestal to give more drop

[G and J]

25 minutes ago, joth said:

You can't use a double check valve or similar as there's not guaranteed to be enough pressure in an overflow situation to open it. Drains normal stop back flow using gravity, that's essentially what the standpipe is for in your setup, and in a washing machine outlet, and the tundish mentioned above is essential the same idea. The problem is water softeners don't have much vertical drop hence the very crammed standpipe and risk of it filling up and syphoning back. Our softener is installed on a meter high pedestal to give more drop

Our softener here has a through the wall type overflow, which is what I’ll do in the new pad.  That’s ok for us as the water softener will sit in our garage outside the airtight envelope.  Not sure how one would do it if it was inside the airtight membranes.