Quest to Stop Dishwasher Drain Gurgling.....

[capt'ngrumpy]

What you believe and the AU Standards are 2 totally different things.
A coupled connection (totally sealed) causes siphonage where as a tundish is allowing air to be admitted to the pipe/trap as required in the Au Standards.
Of course you can hook the WM/DW drain pipe into the waste pipe as long as it finishes above the trap seal, that is a given.
The air gap is created by the fact the waste pipe is 40-50mm whereas the drain pipe from WM/DW is 25mm give or take.
FWIW there is a lot more to plumbing than asking the lady at Bunnings what you need then screwing/gluing a few pipes and fittings together.

FYI the outdated method I refer to was a coupled connection to a 40mm, or larger, trapped standing-wastepipe. This comprised of a barbed fitting screwed into bush with holes drilled in it, to prevent being totally sealed.
It is not often that a diswasher is discharged above a tundish. Especially in a domestic installation.
The legal height of air gap for a discharge pipe above a tundish is 25mm.
Then again you would know this.
I find your comment of the asking the lady from bunnings quite insulting.

[BobL]

Don't mean to burst your bubble Bob, but if there isn't a trap incorporated in the waste drain of the coffee machine, then technically this is not legal.
The waste from coffee machines is usually via gravity, not pumped.

For many years I had the coffee machine drain connected to just above the sink trap using a 2.5m length of hose (red line). The hose went through a hole in the bench top and followed a very shallow (5º) run behind the dishwasher to the sink cupboard - the shallowness of this run repeatedly blocked this hose by the small amounts of coffee grounds over time settling out. This was at times a nightmare to unblock and I even had to occasionally use compressed air to unblock the drain hose.

CMdrain.jpg

When I got my new coffee machine I connected the drain to a 1.5m long 20 mm Black poly which dropped through the same hole in the bench top, and then vertically down through a kitchen cupboard and wooden floor n (purple line), into the basement under the kitchen. Here there is a 20 mm black poly right angle bend connected in turn to a 2.5m length of black poly that slopes at an angle of about 30º down to and connects to the sink waste line under the kitchen. With this degree of vertical drop the grounds are easily carried to waste even by the small amounts of drain water output by the coffee machine.

I realize none of this is probably "legal" but it works, no blockages and no discernible smell.

[capt'ngrumpy]

As long as you're happy with it Bob, I ain't telling anyone.

[Sterob]

Your question was will this work or not, I will say not. As per response above the design of the trap is to keep the open sewer smell out of the house.
how noisy is your dishwasher?? I not wish to sound harsh, but since dishwashers have been made they have connected them this way, early days the plumber would cut a hole in the side of the trap. Nowadays this is a moulded barb fitting. How old is your dishwasher??
given the number of dishwashers connected worldwide in this exact way if noise was an issue then why is there not more people looking to find a solution? My dishwasher makes noise but not enough to bother me.

Its very noisy. The dishwasher is new ( Bosch) and I've had 2 plumbers look at it, with no joy. I have the molded barb, that you mention.
The home is open plan with the kitchen and family room together. The gurgling, we can hear over the tv.....

[Sterob]

I honestly can't see the sewer gasses working their way through the diswasher plumbing and drain pump. The sump in my D/W always has water in it too, so I assume that works as a trap.

However, with your proposed solution, I wonder whether the escaping dishwasher waste water might syphon out some of the sink trap water? The solution I use is to plug the sinks when the dishwasher is running. It almost completely eliminates the gurgling sounds when the dishwasher pumps out the water. We have the integrated plugs with waste baskets.

Yes, plugging the holes does dampen the noise but SWMBO does not want to do that......

[Sterob]

My coffee machine waste is plumbed in after the sink S bend and there's no syphoning of water out of the S bend. OTOH the volume of waste water from the coffee machine is significantly less than from a dishwasher.

Thanks Bob....interesting.

[Sterob]

I've had another thought.....
What if I add 2 more P Traps under both bowls?

It complicates the pipework, but It apears to solve both problems.
Fumes and DW noise.

Thoughts?

Steve

20240320_182733.jpg

[capt'ngrumpy]

I've had another thought.....
What if I add 2 more P Traps under both bowls?

It complicates the pipework, but It apears to solve both problems.
Fumes and DW noise.

Thoughts?

Steve

20240320_182733.jpg

Do not do this. Double trapping is an absolute no no. Gee 2 plumbers with no results. What tests did they carry out?
1- check the nipple/barb on trap is clear and has been drilled out to the total bore.
2- check the hose hasn't been squashed or kinked. This may involve pulling the d/w unit out completely.
3- check the impeller on the pump in base of d/w if possible, for foreign objects.
4- consider contacting the supplier/manufacturer , you may have a lemon.

[Sterob]

Do not do this. Double trapping is an absolute no no. Gee 2 plumbers with no results. What tests did they carry out?
1- check the nipple/barb on trap is clear and has been drilled out to the total bore.
2- check the hose hasn't been squashed or kinked. This may involve pulling the d/w unit out completely.
3- check the impeller on the pump in base of d/w if possible, for foreign objects.
4- consider contacting the supplier/manufacturer , you may have a lemon.

Ok...thanks. I won't do this.

[r3nov8or]

Yes, plugging the holes does dampen the noise but SWMBO does not want to do that......

Well, that's her problem.

We've always had the gurgling since the kitchen reno and went with dual sinks. Two different DWs, same thing. We have solar, so we run the DW during the day when there is usually no-one hanging around or watching TV.

[jack620]

Well, that's her problem.

I thought the same thing, but wasn’t brave enough to say it! I mean, it’s a free solution and it works.

Steve, show your wife this thread.

[rwbuild]

For many years I had the coffee machine drain connected to just above the sink trap using a 2.5m length of hose (red line). The hose went through a hole in the bench top and followed a very shallow (5º) run behind the dishwasher to the sink cupboard - the shallowness of this run repeatedly blocked this hose by the small amounts of coffee grounds over time settling out. This was at times a nightmare to unblock and I even had to occasionally use compressed air to unblock the drain hose.

CMdrain.jpg

When I got my new coffee machine I connected the drain to a 1.5m long 20 mm Black poly which dropped through the same hole in the bench top, and then vertically down through a kitchen cupboard and wooden floor n (purple line), into the basement under the kitchen. Here there is a 20 mm black poly right angle bend connected in turn to a 2.5m length of black poly that slopes at an angle of about 30º down to and connects to the sink waste line under the kitchen. With this degree of vertical drop the grounds are easily carried to waste even by the small amounts of drain water output by the coffee machine.

I realize none of this is probably "legal" but it works, no blockages and no discernible smell.

That is illegal if there is no s trap at the point of connection. Nothing to stop vermin (cockroaches) from travelling up it regardless of how often you use and flush it but more importantly the bacteria that breeds in any black or grey water drain will eventually contaminate your machine especially if your are away from home for an extended time ie: holidays, medical problems.

[BobL]

That is illegal if there is no s trap at the point of connection. Nothing to stop vermin (cockroaches) from travelling up it regardless of how often you use and flush it but more importantly the bacteria that breeds in any black or grey water drain will eventually contaminate your machine especially if your are away from home for an extended time ie: holidays, medical problems.

The bacteria is likely to be the least of my worries compared to the 5-6 double shots of espresso I have daily.

[mic-d]

The bacteria is likely to be the least of my worries compared to the 5-6 double shots of espresso I have daily.

Bob, how many grams of coffee are in those double shots? The boss has until recently had 2 x 22g shots a day but cut back to one.

[Sterob]

Well, that's her problem.

We've always had the gurgling since the kitchen reno and went with dual sinks. Two different DWs, same thing. We have solar, so we run the DW during the day when there is usually no-one hanging around or watching TV.

Actually, its 'our' problem......

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I thought the same thing, but wasn’t brave enough to say it! I mean, it’s a free solution and it works.

Steve, show your wife this thread.

Not A Chance....lol