How Do I Work Out How Many Gallons Of Water In A Pond?

7 Answers

Rebecca Hunt Profile
Rebecca Hunt answered
This will be easy to work out. The things that you will need to work out how many gallons the pond holds are:

-         The length of the pond
-         The width of the pond
-         The depth of the pond
-         Measuring tape to find out these measurements
-         A calculator
-         If the pond has an irregular shape just make as close to an estimate as you can.

1.       Write down the depth, width and length of the pond. The depth will probably have to be averaged.
2.       Multiply the width and the length and you will come out with square feet. Multiply the pond's depth by these square feet. You will now come out with cubic feet.
3.       There are 7.5 gallons per cubic foot. You then need to multiply these cubic feet by 7.5. This will give you the answer.
4.       If the pond is round, find out what the diameter is. This is the length that runs across the pond's circle. Halve this diameter. You will then come out with the radius. You then have to square this radius. You multiply it and times itself. Multiply this number times 3.14 (Pi) and you will come out with the surface area's square footage.
5.       Multiply this number by the depth. You will come out with the cubic feet. Multiply these cubic feet by 7.5. You will then have your answer.

A person might want to know the amount of gallons that their pond holds to find out the amount of helpful bacteria and various water treatments that needs to be added. It will also help to determine the pump size required. Fish medication, beneficial bacteria and dechlorinator are all calculated in ounces for every gallon of pond water. It will therefore be necessary to know the amount of water in the pond.
Anonymous Profile
Anonymous answered
My pond is 11 feet by 4 feet by 2 feet 6 inches how many liters will it hold
Julii Brainard Profile
Julii Brainard answered
If the pond is a very regular shape (perfect semi-circle or rectangular) you may be able to work out the volume using geometry. For instance if the shape is rectangular, then measure sides in cm, and

Volume in litres = Depth * Width * Length / 1000

Multiply litres by 0.2642 to get American gallons, and by 0.22 to get Imperial (UK) Gallons.

Most ponds are an irregular shape, though. If it's from a store-bought pond mould, you may be able to ask the manufacturer or even go back to where you bought it and ask how much capacity it had.

Else, you are not going to get an exact answer. The following rule of thumb may work within a reasonable margin of error, though. It's the same formula to use if the pond is a hemisphere shape.

Measure perimeter length of pond (P). Measure depth of pond at deepest point (D). Guesstimate Volume (V) of pond as

V in litres = 0.3377 * P * P * P / 1000
Anonymous Profile
Anonymous answered
Pond measures 13ft by 18ft
Anonymous Profile
Anonymous answered
Pond is 15ft x 9ft x 6ft deep what is this in gallons as both pump, filter and
uv have now all stopped fuses checked

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