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Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 12:26 am
by Asimo_99
Hi there,

I’m hoping someone can help me with my plumbing issue.

I have had a new kitchen installed and as part of that a new Vellamo double sink. My fitter has connected a new waste trap to the sinks however when I run the water from the tap I can hear gurgling noise from the strainer and water running loudly through the waste trap. I can also see bubbles/water at the bottom of the strainer as if the water is not draining.

As this is a new install, I didn’t expect to hear so much noise. I am sure something isn’t correct in the setup (see attached picture). I have spoken to my fitter and he says he has done everything correctly. He said that the issue may be due to the exterior waste pipe not going directly into the drain (it stops above the drain cover on ground level) causing trapped air however I never had this issue with the old sink. He has suggested that I buy an additional waste pipe kit for the right hand side sink and then connect the two systems together after the p-trap.

Looking online, the only thing I have noticed different on my system is that the pipes from the strainer bend 90 degrees almost straight away whilst most others seems to have significant vertical drop before the 2nd sink waste pipe attaches. Could this be the reason for the noise etc? I have also seen on youtube, for 2 bowl sinks an alternative design where the waste for both sinks meet in the middle before going through the p-bend however don’t think screwfix/toolstation etc sell this style.

Any comments/suggestions would be appreciated.

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 8:49 am
by dewaltdisney
Have you tried pushing the plug/strainer in on the small sink? The main sink draining will push out of the other as the water drains and the level rises temporarily. Also, the air sucked in from the second sink will cause gurgling. Try closing it as an experiment.

DWD

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 9:38 am
by Someone-Else
The current external pipe stopping just above the drain has nothing to with it, if anything it is good as it lets air in to the pipe work.
As water rushes down one waste there is nothing to stop anything (air, water or smell and since sound travels through air..........) coming up the other waste as the 2nd waste is connected to the first before the trap. (Vaguely like connecting two tins via a piece of string, keeping it taught then speaking into one and hearing at the other)

If each sink had its own trap before joining there is a slight possibility that if the main sink is filled with water, then the plug pulled, the velocity of the water could create enough vacuum to pull the water out of the smaller sink trap (Leading to smells at a later date, but cured when the small sink is used) This sometimes happens in bathrooms with a shower close by.

The best option would be to give each sink its own direct outlet (with trap) to the external drain.

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 9:57 am
by aeromech3
I found the same noises after changing to a double sink, my trap is to the bottom left out od view and the washing machine joins from the right; I think the only way to lesson the noise following DWD explanation is to have a trap for each sink.

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 4:25 pm
by Asimo_99
dewaltdisney wrote:
Fri Jul 03, 2020 8:49 am
Have you tried pushing the plug/strainer in on the small sink? The main sink draining will push out of the other as the water drains and the level rises temporarily. Also, the air sucked in from the second sink will cause gurgling. Try closing it as an experiment.

DWD
Yes, I have tried pushing in the plug and it does reduce the gurgling noise. As both of the sink bowls can be used as the primary bowl I am not keen on having to keep one plug permanently closed. If possible I would prefer to solve the issue by modifying the pipework.

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 4:27 pm
by Asimo_99
someone-else wrote:
Fri Jul 03, 2020 9:38 am
The current external pipe stopping just above the drain has nothing to with it, if anything it is good as it lets air in to the pipe work.
As water rushes down one waste there is nothing to stop anything (air, water or smell and since sound travels through air..........) coming up the other waste as the 2nd waste is connected to the first before the trap. (Vaguely like connecting two tins via a piece of string, keeping it taught then speaking into one and hearing at the other)

If each sink had its own trap before joining there is a slight possibility that if the main sink is filled with water, then the plug pulled, the velocity of the water could create enough vacuum to pull the water out of the smaller sink trap (Leading to smells at a later date, but cured when the small sink is used) This sometimes happens in bathrooms with a shower close by.

The best option would be to give each sink its own direct outlet (with trap) to the external drain.
Thanks for clarifying the external pipework isn’t the issue.

I think you’re right and having a dedicated second trap for the 2nd sink is the way to go. That’s a good point about a potential vacuum being created but will most likely switch between sinks so hopefully that won’t be an issue.

I’ll speak to my fitter about installing a second trap and hopefully that resolves the issue.

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 4:37 pm
by Asimo_99
aeromech3 wrote:
Fri Jul 03, 2020 9:57 am
I found the same noises after changing to a double sink, my trap is to the bottom left out od view and the washing machine joins from the right; I think the only way to lesson the noise following DWD explanation is to have a trap for each sink.
Thanks for that. The system you have with both drains meeting in the middle before heading into the trap is what I could see on youtube for double bowl sinks but I can't find this anywhere local to buy. Although it's good to know now that even with changing to this system that I might have the same noise issue. I am planning to go ahead with installing a second trap so hopefully that sorts out my issues.

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 8:46 pm
by arco_iris
:welcomeuhm:

You could investigate (via google) McAlpine MACVALVE-2 self closing trap (you'll need two, together with a right-angle adator T4U for each) and some other solvent-weld elbows and a Y piece to join the two traps together and thence to the outlet.

Well I know what I'm saying, will take a bit of jiggling, won't be cheap, but will make a neat, low-profile, low maintenance, under sink system without impacting on cupboard space.

Too difficult to explain in detail here for no good reason, PM me if you want help with this solution. Pretty easy DIY.

Sink Waste Trap Gurgling/Noise

Posted: Fri Jul 03, 2020 9:35 pm
by Someone-Else
Would Asimo_99 not need 10 posts to be able to PM anyone?