Black and Grey Water tank
From Skoolie.net Wiki
These tanks are hooked to the drains of your sink and lavatories and hold the waste water for dumping.
The way many RV systems work is to use a semi-pressurized system...in other words, the fresh tanks are gravity-feed to a pump that keeps the system pressurized constantly. The pump is usually right next to the fresh supply tank. When you open a valve in the sink or shower, the pressure drops and a small switch on the pump senses the drop; that starts the pump to restore pressure. As long as the pressure doesn't stay at a high preset level, it runs the pump. When you shut off the water, the system pressure builds up and shuts off the pump.
NOTE: shutting down the pump at night is a good idea (install a kill switch), as it can start up from time to time to repressurize a slow backflow leak, and that can be VERY annoying when taking a nap.
The only time you don't use the pump is when you are on shore water with a freshwater hose hookup. Between the shore hookup and the pressurized side of the pump is a check valve; this prevents water backfilling to the shore connection and overflowing out the fill pipe, out the shore connection. I believe that most pumps have a backflow check valve to prevent backfilling towards the tank when you are connected to shore water.
BTW, it's a VERY GOOD IDEA to use as few sharp right-angle bends as possible in the fresh plumbing: the small pumps available only push so many CFM at a time, and any bend or restriction adds friction and slows the flow. Use continuous PEX tubing as much as possible. IIRC, one 90 degree bend is equivalent to adding 10 feet of tubing to the run, and that's a LOT of restriction. If at all possible, make sweeping turns with the tubing instead of using elbows and such. And use the next size larger diameter tubing if possible, this will also help with flow restrictions. Heck, use the largest tubing you can get, say 3/4 inch.
This wil give you more flow and an apparent higher volume of water for showers, rinsing dishes, etc.
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Posted: Thu May 18, 2006 10:36 pm Post subject: gray water tank
Why use your idea ONLY for gray water? Couldn't it work for black and fresh also? I know in a 55 gallon drum, if you supply just 5lbs of pressure with the valve open you get a tremendous amount of water out of it. I've done it! One of those itsy bitsy car air compressors that cost less the $10 does the trick. Heck the pistons about the size of a thimble.
I'm having to resort to rubbermaid all the way around for this attempt. I figure on the fresh I'll either suck the water out of it OR pressurize it on demand only.
I'm thinking to keep shore water from "blowing out the seals" I could install one of those "y" connectors thats switches one or both sides on/off and use that to turn the tank off when connected to shore water.
I'd really appreciate any feedback on this before I get too far along. We'll be using the rubbermaid 50gallon square tanks.
Also I foudn out that lowes sells a 26 gallon "moving tote" for $17 rated at 500 lbs. Thats far more then is necessary. It's made by "glacier living"
