We just bought a small TT with tiny tanks (15 gray, 9 black). We also bought a 15 gallon overflow tank, since we know we'll be needing it at non-full hook up campgrounds - probably daily for grey water.
To maximize the length of use between emptying the tanks, we have done the following, as necessary:
*use campground facilities during the day to help the black tank last longer, and we also only do #1, never #2 unless it's an emergency, in the camper toilet (sorry if TMI).
*strictly limit the amount of toilet paper used, which helps both with making the tank last longer, as well as keeping the sensors from gumming up as quickly. *flush the black water tank (some campers have one built in when emptying the tank for last time; we have a simple wand sprayer that we attach to a hose and stick down the toilet - NOT the drinking hose!!). This has worked pretty well in every camper we've had so far in keeping the sensors relatively accurate (as well as the bathroom habits listed above).
*don't empty the black tank unless full or nearly full. Add water, if necessary, if you need to empty before it's full.
*take Navy showers to limit water going into grey tank. We use the campground showers if they're clean and have a/c in the summer. With kids, I'd definitely do this!
*wash dishes outside like tenters do, if necessary. If you have an outside shower, this is very easy. Set up a small folding table and use 2 dish tubs on it - one for soapy water (only an inch or two is plenty) and one for draining dishes with an rv size dish drainer in it; use the sprayer to rinse dishes into the soapy water tub. If you don't have an outdoor shower, attach a second hose to your water connection with a Y connector. Good for rinsing dirty/sandy feet off, too.
When we had a larger TT with 30 gal. tanks, the black tank lasted a week using the above methods, and the gray lasted about 3 days. There were only 2 of us, so that makes a big difference, compared to having a family/kids.
Beth and Joe
Camping Buddies: Maddie (maltese/westie?), Kramer (chi/terrier?), and Lido (yellow lab)
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