basement sink - backwater valve

caufmantr

Hello-

I have a question on adding a sink into a basement - I was planning on tying into the main drain drop from the upstairs kitchen, however I am questioning the backflow / backwater valve - can I add this to the drain line of the sink before it ties into the main drain (between the P-trap and the maindrain)? Most articles I see reference putting these valves under the concrete which i understand for toilets, showers, .... but the only thing I need to protect here is the basement sink.

Any advice is much appreciated,

Todd

VIPlumber

Backwater valves are normally used on the main house drain before it connects to the city drains.

What you are looking for is a check valve, either swing or spring. Having said that I don't believe that it's normally necessary to install them on a simple sink drain unless there's a problem with your drains backing up? Or are you a worry wart Todd?

caufmantr

Thanks - could be reading too much into this, but I see code requirements for a backwater valve for any fixtures that are lower than the lowest manhole cover. Trying not to have to breakup concrete and put in a typical backflow valve to the main sewer line, was hoping to have something in-line in the drain for the sink before it ties into the main vertical drain going under my slab......



Are you saying this isn't necessary either way?

Thanks!

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VIPlumber

Where are you located? That's not in my code requirements here.

If protection from backup/flow if what you're looking for, then put a check valve in your drain line.

caufmantr

Thanks, I will likely add a check valve then as I depicted in the drawing. For reference, I am located in Michigan.

Thanks again,

plummen

that check valve in that small line is going to play hell on you if you ever have to have that sink line cabled ,it will go through but it will be tough getting it back

caufmantr

I should be able to put the check valve in a closet that is planned to be built around the main drain line anyways - hopefully that will help if any service is required - still sounds a lot better to me than breaking up concrete to put in a backwater valve for just a sink....

TheEplumber

I am required to put BW valves on fixtures located below the manhole rim. On new construction I have to isolate the basement fixtures on the valve- no other fixtures can be on it. You can buy small(1.5 &2") BW valves with removable tops for your purpose. If your worried about the main backing up into your sink, put it in.

caufmantr

Thanks, I have a bathroom pre-plumbed on the other side of the basement that has a bw valve under the slab.
For the sink, does the bw valve have to be under the concrete or is something inline with the drain ok, per my previous sketch location? I am not really worried about backup in this area, but I am pulling a permit for the basement so I gotta do it right.....

Thanks!

TheEplumber

the bw valve needs to be readily accessible in the wall or floor.

ben's plumbing

imo you really don't need this ck valve installed in system overthinking this....and if installed needs to be accessible.....I believe that is code in your area also..ben

#1plumber

Where I am from they will not allow a check valve in line with any fixture. The back water valve has to be installed on the main line coming into the house under the concrete. And besides, if water does back, up its going to come up through your floor drain first if its not protected.