What Size Fresh, Grey, Black Water Holding Tanks?

[Gary Hatt - Publisher BCM]

In my first bus conversion, an MC-7 Combo bus, there were two stainless steel holding tanks, each with a capacity of 250 gallons. Those two tanks were custom-built to fit into one bay in the belly of the bus.  I could go a month before having to dump and fill them when I traveled alone.  If my girlfriend was with me, it would last about three days. 

Yes, I know, a gallon of water weighs 8.3 lbs., and additional weight in a bus conversion can be an issue.  If both of my tanks were full at the same time, I would be carrying two tons of liquid in my bus.  But everyone knows there is never a time that both tanks would be full at the same time.  You fill the fresh water tank, and over time, it gets transferred to either one combination grey/black tank or two separate grey and black water tanks.  Carrying one ton of water or sewer in a bus is quite a bit, but most buses can handle that much extra weight if your bus is not loaded with granite countertops or other heavy objects.

Another advantage of having large holding tanks is that you pay a fixed price per dump, not per gallon, at most dump stations.  So for the $15 that some places are charging now, you would get more bang for your buck with larger tanks of course.

Bottom line, if space and money were not an issue, what size Fresh, Grey, and Black water holding tanks would you build into your next conversion?

[plyonsMC9]

Our original MC9 / Moose Creek Conversion ( #001) had only a 70 gallon grey water tank, and for us and our usage patterns, it wasn't enough.  We like to boondock usually for about a week give or take a day or two.  And that just wasn't enough.  Other folks may use less/more. 

For our DL3, we chose 150 fresh / 150 grey capacity.  Not 100% certain what the black tank capacity is, but we never seem to get close to filling that up.   The 150/150 works great.  We've only put a few thousand miles on the DL3, but those tank sizes are working pretty well for us.

Take care all, Phil

[Iceni John]

Fresh 220, grey 115, poo 65.   They're the largest that fit my bus.