When it Comes to Water Wells, What Does Flow Rate Mean

 Flow rate and water well yield

Flow rate and water well yield

Flow may seem like a simple term, but it is an important way for well professionals to determine whether a well can adequately meet a family’s needs. The flow refers to the amount of water coming from the well. The flow rate measures the gallons per minute coming from the well. Flow rate is tested when a well is initially drilled and can be tested again to determine if there are problems with the well.

The average American household needs 100 to 120 gallons per person per day, and a flow rate of about 6 to 12 gallons per minute. This requirement should be higher if it serves a home housing a large family or there are large water demands.

Low flow can have a number of causes.

The well could be drying up, which can be resolved through drilling and hydrofracking. It could also be the result of a badly placed well pump and clogged pipes. This was the cause of a dry well during a 2013 Skillings & Sons project featured on the PBS show This Old House. This 1935 home in Essex, Mass., was being remodeled for the homeowner’s aging parents when the well unexpectedly ran dry.

Roger Skillings, president of Skillings & Sons, was onsite overseeing a geothermal well drilling when the home water well problem sprang up. He was called in to fix the well and was featured on the episode.

The best way to determine how much water regularly flows from a well is by conducting a flow test. The Essex house flow test showed that water was flowing at 3 gallons per minute, below the 5 gallons per minimum for home use. Next, Skillings checked the water depth and the pump depth to see if the pump was installed at the right level. The water depth came in at 126 feet and the depth of the pump was 160 feet. The difference between the water level and well pump did not leave much allowance for water use.

Skillings then pulled the water pipe from the well to determine if there were any other problems. The crew found the lower levels of the pipe were caked in rust, indicating high levels of iron and the need for a filtration system. A drill bit was then lowered into the existing well bore to clear the well of debris and sediment. This was done in hopes of clearing the rocks, soil, and minerals blocking the fissure that carry water through the bedrock deep below the ground.

Once the well bore was cleared, a pump was installed deeper than the previous pump and another flow test was done. It showed the well was pumping 30 gallons per minute, which is more than adequate to meet the home’s needs. Skillings’ troubleshooting saved the homeowners from the expense of having to drill a new well and connect it to the home.

Determining flow needs

Homeowners can do some quick calculations to see what their home’s flow rate should be before calling a professional.  Count the number of water fixtures in your home, including showers, faucets, outdoor water spigots and water-using appliances like dishwashers and clothes washers. Calculate 1 gallon per minute for each appliance. That will show you the average gallons per minute needed for your home.
For example, a small home with one bathroom would have the following fixtures:
1 shower
1 toilet
1 bathroom sink
1 clothes washing machine
1 refrigerator ice maker
1 dishwasher
1 kitchen sink
1 outdoor spigot
= 8 gallons per minute

If you suspect your well’s flow rate is too low to serve your home’s needs, or that it has suddenly dropped unexpectedly, there could be a number of causes, including problems with the well, the well pump, clogged pipes or low water pressure. Skillings & Sons can advise you on the problem and help homeowners determine the cause of low flow.