It comes down to how powerful the washing machine pump is... Now, this check valve has to have a reasonable bore, what's a washing machine outlet - 3/4" at least? The big risk here - ok there's two - one is, as Pinoke says, you might end up with sewer gas being sucked into the place, which, in a well-sealed house (as most are) could be lethal, maybe even explosive. The other risk, more likely, is a failure or blockage of the check valve which could result in raw sewage being siphoned back into your basement. If you chose this route, I wonder if your insurance would pay out if something went wrong. Don't get me wrong, provided the lift's not too great (and you'd definitely need a trap etc some distance ABOVE the sewer line to reduce the risks, this ought to work, however, and I'm not sure about whether all ejector pit things have to be buried - I've seen one of these ejector units and they don't look that complicated or expensive, and the BIG advantage is, you can have a laundry sink down there too, which will drain into one of these gizmos - and will pump itself out up into the sewer when it fills - and these things are designed for the job and ought to do it more efficiently and safely - and when you sell the house, you won't have to rectify anything, as if you take the cheap route, you might be forced to disclose it, or an adept building inspector may spot it and put you in an unfavourable bargaining position.

I've done a poor job of explaining and your question got me thinking. What I meant to say: The main sewer lines and main DWV trunks all sit directly across the basement on the opposite wall (about 14' away). The joists run in the same direction (from the washer to the sewer/dwv). I'd use a wash basin and the gray water pump to lift the water into a pipe in the basement ceiling that would then run across and dump into the main sewer or existing DWV (there will be adequate depth for the slope). What your question got me thinking: The washer is going in a few feet from the the DWV for the first floor kitchen sink. Perhaps I can just tap it into the DWV that comes down from the first floor kitchen?

Bleach is fine as long as you're not on a septic system. Some Comet cleanser on a bottle brush might work better. Are you talking about rust inside the drain? If so, don't worry about it. The rust will just come back. As long as the drain doesn't leak. If it does, replace the pipe with PVC. For that, you'll likely have to call a plumber unless you're handy and can do it yourself. (Sounds like you'll have to adapt PVC to metal pipe.) If it's on the outside and you're worried about aesthetics, the best paint that I've used is Rust Bullet. Order from Amazon. But it costs over $20 for 1/4 pint unless you can find it locally and avoid shipping charges. Automotive parts store might have it. Edited to ask: Will you be able to see any of this once the washer is installed?

I guess I’d like to implement the best solution for any possibly scenario. I would have to speak to the plumber and/or the contractor to understand exactly what goes under the tile or can go under it to make it waterproof.. as of this moment I don’t know what the plan was. In my mind it would be like the shower, how they put down that black vinyl waterproof barrier, but maybe that’s not what they do...? I have bare plywood right now so I can do whatever is best- just have to understand what that is, so I’m looking for some input from anyone with experience. I’ll have a shut off valve for the water supply, so that should take care of any major water supply issues (if I remember to turn it off), so mainly a backup plan if the washer overflows, leaks, or malfunctions in some way when draining (plumbing backup?)