How to measure water usage for drip tape

1. How to measure water usage using drip tape.

Drip tape uses extremely low water pressure. If too much water pressure is used, the drip tape emitters will rupture. A 100 foot run of drip tape with emitters every 12 inches does quite well between 4 and 10 PSI. The average GPH (gallon per hour) of each emitter is between 0.25 GPH and 0.50 GPH (based on water pressure).

a. Use a water pressure gauge (figure 1a.) or use a water pressure attachment (figure 2a.). This is the recommended method.

b. If you do not use water pressure gauge or pressure valve then you can experiment by viewing the water flow on your 100 foot run of drip tape and then mark a place on the handle to your water hookup connection. I have found an exact point on my water on/off  valve handle. It is shown in figure 1b. below.

2. How to figure water usage per minute:

a. The easiest way to figure water use per hour is the fill a 5 gallon bucket with your garden hose (figure 2a.) Document the time it takes for the 5 gallon bucket to fill up. It took me of 9 minutes to fill a 5 gallon bucket.

5 / 9 = 0.55
5 gallons divided by 9 minutes equals 0.55. This is a little over 1/2 gallon per minute.

b. How to figure water usage for a 3 hour period:

180 X 0.55 = 99
3 hours equals 180 minutes. 180 minutes times 0.55 gallons per minute equals 99 gallons of water usage in a 3 hour period.

3. How to estimate cost of water usage for 3 hour period if using county water supply.

a. Brunswick County NC charges $3.05 per 1000 gallons on water usage (see reference)

1000 X 3.05 = $.003 per gallon
1000 gallons times the rate of $3.05 charge per 1000 gallons equals $.003 per gallon.

b. Cost for 99 gallons of water usage in a 3 hour period

99 X .003 = 0.297
99 gallons times $.003 per gallon equals $.297 -OR- rounded off equals $0.30. It cost 30 cent to water a 100 ft. garden row using 100 ft. of drip tape in a 3 hour period.

4. How to figure your monthly watering expense using county water.

If you water for 3 hours every other day and assume the monthly watering frequency to be 15 days per month then you can estimate the monthly cost of watering a 100 ft. row using a 100 ft section of drip tape:

$0.30 X 15 days = $4.50 per month

In conclusion the cost would be $4.50 per month for watering a 100 ft. garden row using drip tape.

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