"Steve Barker" wrote:

Ours is in gallons. Can't imagine why they would measure water in cubic
anything. Liquids are measured in gallons.

You need to get out a little more and expand your horizons. The quantity being
measured has a great deal to do with the units of measure. For example, time can
be measured in years, months, days, hours, minutes or seconds...

In the case of residential water, many water systems use "units". A common
conversion for residential water units is 100 cubic feet or 748 gallons.

To the OP who was billed for 2 units (presumably in a month), that equates to
1498 gallons, or around 50 gallons a day. Pretty much the average per person
usage in the US.