How long can you hold it?

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Well-known member
Aug 15, 2005
Tempe, AZ
Is there a general guideline for how many days you can camp before your black water or grey water tank needs to be emptied?  How many gallons per day per person is normal?  I realize it depends entirely on the usage mode of the individuals involved but wondered what some of you experienced?  We try to use the campground facilities to the maximum if it is convenient.

We have 100 gallons of fresh water, 50/50 of grey and black. My wife and I go three days without any measurable conservation including showers when we are traveling.

If we know we are going to be boondocking the paper plates come out, short "Navy" showers, dishwater down the toilet, and other more drastic measures will get us by up to 6-7 days.

If you have a good deodorant you can probably even beat that.  ;) ;)
We have often gone a week without hookups by applying common sense to water conservation.  The longest time was 11 days.

We don't have exceptionally large tanks, 74 gal. fresh water, 60/40 gray and black water.
We can go at least a week without having to dump holding tanks or fill water tank. We have an 80 gal. water tank and 55/45 holding tanks. Washing dishes and showers use the most water. We have a double sink and use it when washing and are really conservative of water when showering.

Our experience is about the same as the others.  The gray tank always fills first, but if you can dump dish water elsewhere (or pour it into the toilet), that helps a lot.  We can often get 10 days of use on the black tank, so adding some gray doesn't hurt much.

However, some folks we know of seldom get more than 3 days before they need todump tanks. It all depends on your willingness to conserve.
Taking full showers and doing laundry we can go 2-3 days without dumping. Taking conservation measures such as others have described, we can go 10 days. As Gary points out, the gray tank will fill first, so work around anything that empties into the gray water tank, e.g. sinks, shower, washing machine.
By myself, with 50 fresh and 40 gray & 40 black, I went over 2 weeks. No odor from the black ?tank and it dumped fine. (I used Fred Thomas' advice to use extra water in the black.)

Of course I cheated and let the gray run in mother-in-law's pasture! So, if you can shower somewhere else once in a while or park in a horse pasture...
caltex said:
So why do the RV manufactures insist on making them the same size?

I don't think they do. Some models of some manufacturers have the same size B/G tanks, but other models have different sizes. e.g. two of the three versions of of the Vectra have the same size tanks (54/54), but the third has different sizes (62/54). Similar story with some of the Monaco coaches.

So your question is still valid for those that have the same size tanks and I've never figured out why, other than the available space due to a particular floorplan &/or bay storage options - which could be with the two 40' Vectra models which have different tank ratios for the same size coach.

This might have been a good question for me to have asked when I toured Monaco's chassis plant.
lucyakers said:
and let the gray run in mother-in-law's pasture!

I won't tell  :).  Of course, that would be a big no-no on, for example, BLM land.
We have 60 gal Grey water , 40 Black water, and 100 gal Fresh water tanks on the Eagle and can get by for 10 days before dumping. Conservation as mentioned previously is required.
caltex said:
I agree that the grey tank always fills faster  (2X to 3X) the black tank.  So why do the RV manufactures insist on making them the same size?

We have 50 gal fresh, 40 gal black and 50 gal grey. Only problem is we have a rear kitchen so the grey is split into two separate 25 gallon tanks. Since we use mostly paper plates, the galley tank hardly ever fills. The bathroom sink and the shower empty into the 25 gallon tank. That one fills up in a real hurry if we take showers.  :(
caltex said:
So the real answer is to size then for the convenience of manufacturing rather than the customer?

That's about it! Welcome to the real world.  ;)
caltex said:
So the real answer is to size then for the convenience of manufacturing rather than the customer?

That would be my guess since I haven't seen any other rational explanation for how they're sized. Bruce's 40/25/25 sure seems to suggest that floorplan dictated what they gave him for tanks without the ability to move fluid from one of his tanks to the other.
Our 60 gray, 40 black, tankage is about right.  35/65 might be closer to actual usage, but it's much better than 50/50 :)  Holiday Rambler did a lot of things right when they designed the Endeavor, at least in 1997.

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