How do you switch between holding tanks.
This might be a dumb question. I just purchased a new trailer and I noticed on the display panel it has two black tanks and two grey tanks. The exterior only has one drain location, with two pulls,...
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It would be odd to have 2 black tanks. I've never seen that. Our old trailer did have 2 gray tanks, one for the galley sink and the other for the shower and it's sink. Check your dump valves and see where the pipes go. Very unlikely you have 2 black tanks. Black is for the toilet only (normally) and they rarely fill up, thus the need for only one.
