Help with Holding tank sizes

[jims-retired]

I have a very used 1997 coachmen 300qb 460 efi ford. I did not receive any docs or manuals, but felt confident I could find PDF files online as I did with my previous MH. I haven't been as lucky with specifications for this MH. I would appreciate any help I can get,
Thanks in advance,
Jims-retired

[chuckftboy]

You can measure by dumping 5 gallons at a time in the sink or toilet until full. Simple but time consuming. As for the fresh water, its a little harder as you will need some way to pump in from a 5 gallon bucket. Simple addition and it is accurate

[vsheetz]

Oh no, not math! (-:

[Dutch Star Don]

Actually, do as "chuckftboy" suggested, but start with the water tank. Fill it completely with a hose. Drain it into a five gallon bucket and poor that into the grey tank until filled. Counting the buckets out and in. When you're done, poor the grey tank water into the black tank. When you're done, you'll have all your capacities and clean tanks.