[Bob86ZZ4]

My coach has a 25 gallon black tank and 75 gallon gray tank. My wife and I can go about 5 days before they're full. Now that's with taking showers every day. And not being all conservative about flushing. The rv toilet doesn't use anywhere near a gallon a flush. And we almost never use public facilities. So, if you're out and about during the day and can use the other spots you're going to greatly extend your range. Also, it's not a big deal at all to flush them out. I think it's actually better to flush them out more often than not. Less time for stuff to start growing in there. When I bought mine I thought it seemed odd to have a 75/25 ratio. But, they both seem to fill about the same rate. Another thing, forget about level monitors for them. At least not the in tank kind. I've heard those ones that only mount to the outside work okay. Mine has probes screwed through the side of the tanks. They've never worked as far as I can tell. My previous rv had the same type and those didn't work either. I just make a habit of shining a flashlight down the hole once in awhile to see how high it's getting. And if my gray tank gets full it backs up into the shower so I know it. And my fresh water tanks are under the bed so I cut a hole on the side panelling and put a cabinet door on it. Then I just lift up the door and shine a flashlight in to see how much fresh water there is. I much prefer this method over some electronic means.

I've heard from the guys that have built their own, take your best estimate of cost, double that, then add some more, and you might now be pretty close to what it's going to cost. And you'll never ever ever be able to sell it for anywhere near what it cost you. But, most everybody that's built their own is glad they did and are enjoying their rigs. I didn't have to make the decision of buying/building. I have absolutely no skills to build one.