My 40 gallon waste tanks only hold 32 gallons

[Travelin' Texans]

Originally Posted by Bill Johnson

I have a 40 gallon black tank in my motorhome and I went to visit my son, I don't remember how many days maybe 3 it said it was full. I asked my son where we could dump and he said there is a Wisconsin state park about 45 minutes away. I called a few campgrounds in the area and they all said no dumping unless we were campers. I had my blue boy I think it was the 25 gallon one. It was only half full when we emptied it. We went to the Wisconsin state park and I can't remember what they charged I think it was 10 or 15 and that was okay because in Wisconsin you can't even drive into a park without paying to get in. Now any time it shows full I shine a light down there and check, I bet I could go another week before it would be full. I could see the bottom of the tank when it says full. Never believe the gauges except for my fresh water tank that when it says full I have only a few inches to spare

You are exactly correct! The tank sensors are worthless!
BUT as I was told the OP was only checking tank capacities and not the accuracy of the sensors.
Altough I'm not quite sure how knowing the exact capacity is helpful if the only way to know what's in the tanks is the worthless sensors, which you & I along every rver that's been around a while already knew their accuracy.
If a meter were installed on each faucet & the toilet inlet then the exact capacity of those tanks would be very useful, you'd know exactly what went into them, my OCD isn't quite that obsessive.
When the toilet burps/gurgle when flushed it's nearing full, it's time to dump. When the shower backs up about the time you're all lathered up, it's past time to dump. Typically the galley will last the longest so dump it after dumping the black, then the bath.

[dkoldman]

Originally Posted by Travelin' Texans

When the toilet burps/gurgle when flushed it's nearing full, it's time to dump.
What if toilet is burping but gauge is only reading 2/3rd full?

When the shower backs up about the time you're all lathered up, it's past time to dump. Typically the galley will last the longest so dump it after dumping the black, then the bath.

Do you get to complete the shower, or do you have to run out with the lather still on and dump the tank?

On the serious side, this topic always amuses me. #1 Our gauges have always worked (knock on wood) #2 The Gray tanks always fill at a rate 2-1 to black; so my black tanks is always dumped regardless of level just because my Gray was at 2/3rd or Full tank.

I also think it odd that a lot of users seem to add more water during their flushes, have bathroom sinks that go to the black tank and add all types of stuff like Calgon / Dawn etc.

[Bill Johnson]

Originally Posted by Travelin' Texans

You are exactly correct! The tank sensors are worthless!
BUT as I was told the OP was only checking tank capacities and not the accuracy of the sensors.
Altough I'm not quite sure how knowing the exact capacity is helpful if the only way to know what's in the tanks is the worthless sensors, which you & I along every rver that's been around a while already knew their accuracy.
If a meter were installed on each faucet & the toilet inlet then the exact capacity of those tanks would be very useful, you'd know exactly what went into them, my OCD isn't quite that obsessive.
When the toilet burps/gurgle when flushed it's nearing full, it's time to dump. When the shower backs up about the time you're all lathered up, it's past time to dump. Typically the galley will last the longest so dump it after dumping the black, then the bath.

Right once he knows how much his family uses he will know approximately how many days he can go without dumping unless his feet get wet and his shower turns into a bathtub

[Vibeman]

It seems that some folks consider my testing to be obsessive or compulsive. So be it. I agree it is not critical, or even necessary to have this info, but I only spent 2-3 hours on this test and now I will have and use the results for the rest of the time I own this coach. I feel it was time we’ll spent. I probably spent more time writing and responding to this thread than I spent on the test.

The following could probably be a new thread entitled “Waste water management in a 29m” but I will just add it here as an insight into why I did the testing.
Sometimes we camp in state parks with no hookups. Most are within one day’s drive from home so when we pull in to the park I know exactly how much water we have on board and exactly how much waste capacity we have in each tank. It is a closed system. We both prefer showering in our coach instead of the public showers. By using the info I now have we can adjust our water usage to avoid having to break camp on day 4 of a 5 day outing just to dump the tanks. Waste water generated at the kitchen sink can be dumped into the toilet to increase gray tank capacity for showers if needed. At the risk of really pushing some folks over the top with my behavior, I also measured the output of our shower head and then we each timed an average shower of the other so now I can reliably say how many showers we can each take during a week of camping and not run out of water and not have to dump. We have already done 5 days without dumping, but I think, with careful monitoring, we could comfortably camp for 7 days just using our onboard water and waste capacity.

Others have shared their methods and solutions for waste water management and I thank each and every one that posted. Even though I won’t necessarily use their ideas, I acknowledge there are many ways to skin a cat, and we all do it the way we think is best.

I started this thread to share some information I found out about my coach and others like it. I hope it helps someone.

[JimOIB]

Originally Posted by Vibeman

It seems that some folks consider my testing to be obsessive or compulsive. So be it. I agree it is not critical, or even necessary to have this info, but I only spent 2-3 hours on this test and now I will have and use the results for the rest of the time I own this coach. I feel it was time we’ll spent. I probably spent more time writing and responding to this thread than I spent on the test.

The following could probably be a new thread entitled “Waste water management in a 29m” but I will just add it here as an insight into why I did the testing.
Sometimes we camp in state parks with no hookups. Most are within one day’s drive from home so when we pull in to the park I know exactly how much water we have on board and exactly how much waste capacity we have in each tank. It is a closed system. We both prefer showering in our coach instead of the public showers. By using the info I now have we can adjust our water usage to avoid having to break camp on day 4 of a 5 day outing just to dump the tanks. Waste water generated at the kitchen sink can be dumped into the toilet to increase gray tank capacity for showers if needed. At the risk of really pushing some folks over the top with my behavior, I also measured the output of our shower head and then we each timed an average shower of the other so now I can reliably say how many showers we can each take during a week of camping and not run out of water and not have to dump. We have already done 5 days without dumping, but I think, with careful monitoring, we could comfortably camp for 7 days just using our onboard water and waste capacity.

Others have shared their methods and solutions for waste water management and I thank each and every one that posted. Even though I won’t necessarily use their ideas, I acknowledge there are many ways to skin a cat, and we all do it the way we think is best.

I started this thread to share some information I found out about my coach and others like it. I hope it helps someone.

I for one applaud your analysis. We did exactly the same thing for the same reasons and know we can go 5 days before dumping as well.

[dkoldman]

Originally Posted by Vibeman

The following could probably be a new thread entitled “Waste water management in a 29m” but I will just add it here as an insight into why I did the testing.
Sometimes we camp in state parks with no hookups. Most are within one day’s drive from home so when we pull in to the park I know exactly how much water we have on board and exactly how much waste capacity we have in each tank. It is a closed system. We both prefer showering in our coach instead of the public showers. By using the info I now have we can adjust our water usage to avoid having to break camp on day 4 of a 5 day outing just to dump the tanks. Waste water generated at the kitchen sink can be dumped into the toilet to increase gray tank capacity for showers if needed. At the risk of really pushing some folks over the top with my behavior, I also measured the output of our shower head and then we each timed an average shower of the other so now I can reliably say how many showers we can each take during a week of camping and not run out of water and not have to dump. We have already done 5 days without dumping, but I think, with careful monitoring, we could comfortably camp for 7 days just using our onboard water and waste capacity.

Others have shared their methods and solutions for waste water management and I thank each and every one that posted. Even though I won’t necessarily use their ideas, I acknowledge there are many ways to skin a cat, and we all do it the way we think is best.

I started this thread to share some information I found out about my coach and others like it. I hope it helps someone.

I have done similar but with less scientific measurements.

We have 70 gal fresh water, 61 gal gray and 40 gal black tanks

We have never hit full with normal usage on either waste tanks. Never run out of fresh water. Longest stay was 6 days ( but that is extreme for us) I know we ( two of us) could make 7 days if we knew we had a 7 day trip coming up. Fact is, we never do we just take showers as we like. The gray will always fill at a rate 2 to 1 over our black tank. Our bath sink is plumbed to gray tank NOT the black tank. FWIW our gauges do work, and when / if they do stop, I will likely freak out. If they are fixable; I will have them fixed, especially the gray.