(1) Pumps: The flow rate in gallons per minute or litres per minute.

(2) Water softeners / conditioners: Quantity of undesirable matter that can be removed by a water conditioner under standard test conditions. For ion exchange water softeners, this is expressed in grains of hardness removal between regeneration's and is related to a pound of salt used.

(3) Water filters: For filters, capacity may be expressed in the length of time or total gallons delivered between servicing.

(4) Water heaters: The size in gallons of water of the storage tank (e.g. 40 gal, 75 gal, etc).