Drainage for basement darkroom...

I think my plumber is on vacation for the holidays ( well deserved ) so in the meantime, I will toss a couple questions at you fine folks..

I am installing two sinks in my basement darkroom, one 9 foot SS that will be 36” high in terms of low point and a 6 foot SS that will be the roughly the same. They will be divided by a wet basin transition area that will hold both my Job CPP3 and 16x20 print washer, 9 footer on the left, 6 footer on the right. Right below that wet transition area is my hot / cold water inlet and drain pipe, it will also house my sump pump and related infrastructure. The drain pipe comes in at about 21” off the deck and there is 28” of clearance between the floor and the underside of the wet basin.

I have hunted high and low for answers but I am trying to figure out venting for the two sinks. I am not sure what is code for my area, I am sure the plumber will know once he gets back to me but I am at the point in that the rest of the wet side design will need to reflect the venting needs and I am ready to move on it.

Typically what are people running into here with basement installs and sump pumps, are you going through the major hassle of connecting to an existing vent stack like I would have the plumber do in the crawl space ( $600-$1,000 ) or are air admittance vents doing the trick?

The water distribution is pretty straight forward but this drain venting thing has me stumped.

A Studor vent or similar air admitting vent is what I have used in both darkroom and kitchen installs, all under the advice of a plumber.

sepiareverb said:

A Studor vent or similar air admitting vent is what I have used in both darkroom and kitchen installs, all under the advice of a plumber.

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What type of sump pump, self contained or pump in plastic tub style?

I used one of those air admittance valves on the drain like they use for island sinks in a renovation. It works well and you do not need to go to the expense of tapping into the vent stack. Since you are doing a renovation it is likely you can use the air admittance valve.

Here is a link to the Canadian Home Depot online:

https://www.homedepot.ca/en/home/p.20-dfu-sure-vent-15-2-inch--abs.1000129763.html

If your local plumbing codes are available on a town or county web site you should check that an air admittance device is approved. Some places don't allow them.

I'd look into skipping the pump. Open the drywall under the drain inlet and see if you can tap into it at a lower level. If it's PVC it should be simple, if iron still not a huge deal. That's assuming the drain goes down from there; I'm in a non-basement area (Dallas), but when i grew up in Michigan, the drains went down below the foundation. Usually the lowest drain entry in the basement was the washer drain, up mid-level on the wall and relying on the washer's pump to get the water up there, but those drains went down below the floor (cinderblock basement walls so the plumbing was visible) - we only had gravity drains, no pumps.

Code in my city, IIRC - sinks are sort-of vents, but there's code relating to how far away a sink can be from the in-wall vent, and island sinks require some oddball venting. Many people skip this though, and rely on the sink trap to keep gasses out and on the drain itself to provide a pressure differential for fast draining (not sure of the terminology). Good thing about a darkroom is it doesn't need to be pretty - it can be a little more "industrial" - vent stacks from the sink drain system should be able to tie into an existing stack, even if you have some 2" PVC running across the ceiling and so on.

M Carter said:

I'd look into skipping the pump. Open the drywall under the drain inlet and see if you can tap into it at a lower level. If it's PVC it should be simple, if iron still not a huge deal. That's assuming the drain goes down from there.

Good thing about a darkroom is it doesn't need to be pretty - it can be a little more "industrial" - vent stacks from the sink drain system should be able to tie into an existing stack, even if you have some 2" PVC running across the ceiling and so on.

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Actually the plumber installed the drain, we had to go up to get to the main sewer line, there is nothing below floor level so a pump is mandatory.

As far as being pretty or not, this one will not only be for me but workshops...it is going to be stunning when finished.

What you might need is called an injector pump. It's designed for when you install a bathroom in the basement during a remodel and the sewer line is higher than the john, shower, etc.
If you're just using a sump pump in some kind of tub to catch the water from the sinks, I think a air valve vent would be okay.

Take a look at this: www.popularmechanics.com/home/how-to/a154/12756116.

Failing that, call the building inspectors office.

I'm using a washing machine pump for my darkroom and it works very well.

Ai Print said:

What type of sump pump, self contained or pump in plastic tub style?

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Over my head here. I have a drain line in the floor that I was able to tap into for my darkroom, but no stack available.

Wouldn't worry too much about what is or is not according to "code."

Rich Ullsmith said:

Wouldn't worry too much about what is or is not according to "code."

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You may wish to worry about "code" if you purchase house insurance, and want to be in a position to claim on it anything ever goes wrong and causes water damage.

Adhering to code could also prove important when you sell the property. Better to pay a bit more now than potentially a lot more later should you be caught out and forced to bring it up to code later.