There is a great deal of confusion and misunderstanding when it comes to private wells. When buying land or a house in Bozeman with a private water well it is important to consider well Flow Rate, Well Capacity, and Pump Delivery rates.
Simply stated, Flow Rate is how fast a well can replenish itself. Well Capacity is how much water is stored in the well. Pump Delivery rate is how fast the well pump can push water up to the house.
The Gallatin Local Water Quality District(GLWQD) controls ground water resources for the Bozeman area.
For real estate in Bozeman the most common well water measurement to determine flow rate is Gallons Per Minute which is frequently abbreviated as gpm. Flow Rate measures how fast a well can replenish itself. In other words, how fast water is flowing into the bottom of the well. The Federal Housing Administration (FHA) requires 3 to 5 gallons per minute for older wells and a flow rate of 5 gallons per minute for new wells to pass inspection. The average American household needs 100 to 120 gallons per person per day, and a delivery rate of about 6 to 12 gallons per minute. This requirement may be higher if the well serves a home housing a large family or there are large water demands for a large lawn or garden.
A well that only produces 1 Gallon Per Minute can supply 1,440 gallons of water per day. If the pump is delivering it faster than 1 Gallon Per Minute then the well is using water stored in the well to deliver it. If the well has good storage capacity it can supply water as fast as the pump can deliver it. As such, Flow Rate isn’t the only factor to consider. Flow Rate needs to be taken into consideration with other factors like well capacity and pump delivery rate discussed in this article.
Bozeman is fortunate in that most areas have highly productive wells. Private residential wells typically have flow rates exceeding 15 gallons per minute, and can go above 30 gallons per minute, although additional permits are required for wells exceeding 35 gallons per minute.
It should be noted that hills surrounding the Bozeman area may have lower producing wells, and some areas west of Bozeman also have lower producing wells. Contact our Bozeman Real Estate Experts if you would like to know if a particular area is known to have a problem with lower producing water wells.
Minimum water delivery for use inside a home should be at least 600 gallons within a two-hour period, or about 5 gallons delivered per minute for 2 hours. Some homeowners may find this recommended amount to be less than they ultimately need depending on the size of the family or if there are large outdoor water demands.
EPA restrictions enacted in 1994 limit standard shower heads to a flow rate of 2.5 gallons per minute.
Garden hoses typically place the highest demands on water wells.
A 1/2 inch diameter garden hose that is 100 feet long operating at a standard household water pressure of 40psi will use 6 gallons per minute.
A 5/8 inch diameter garden hose that is 100 feet long operating at a standard household water pressure of 40psi will use 11 gallons per minute.
A 3/4 inch diameter garden hose that is 100 feet long operating at a standard household water pressure of 40psi will use 18 gallons per minute.
It is important to note that a well producing 6 gallons per minute can still support a 3/4 inch diameter garden hose drawing 18 gallons per minute. This is because the well casing stores water, and the gallons per minute delivered is a result of how large the well pump is and how many gallons per minute the pump can deliver.
The question is how long can the pump deliver 18 gallons per minute out of the well, and that is determined by not only the water Well Flow Rate, but also by the Water Well Capacity.
There are a few different ways to look at the amount of water in the well. The first is water storage capacity. A standard 6-inch diameter drilled well can store 1.5 gallons of water per foot. If you know the depth of the well, the static water level, and the pump depth, you can figure out the water storage capacity. Most people don’t know all of this information, but it can be figured out looking at a well log or by consulting with a water system professional.
Flow Rate is different than Delivery Rate. Flow Rate measures how fast a well can “replenish” itself and Delivery Rate Measures how fast the pump can push it through the house.
A typical 3 to 4 bedroom home requires a delivery rate of 8 to 12 Gallons Per Minute. The desired delivery rate, along with the depth of the well determine the size of pump needed. In simple terms, deeper wells require more powerful pumps.
Submersible well pumps are typically offered in horsepower ratings of 1/2 HP, 3/4 HP, 1 HP, and 1 1/2 HP.
A well that is 60 feet deep and has a 1 1/2 HP pump can deliver 27.5 gallons per minute. A well that is 500 feet deep may require a 1 1/2 HP pump to deliver 6 Gallons Per Minute.
If after conducting a flow rate test, the well does not meet the recommended standards, there are some options to increasing flow. If there is space on the property, another well can be dug. This is costly, time consuming and may not get the results the homeowner needs. Existing wells can be improved by a process called hydrofracking, which blasts water into an existing well bore to clear debris and open fissures allowing water to flow through the bedrock.
Hydrofracking does not use chemicals and is different from the hydraulic fracking associated with the oil and gas industry.
In addition, if a well produces below the flow rate that your family requires, a holding tank(typically 500 gallons) or cistern can be installed with proper controls on the well to keep it from pumping dry. The holding tank will provide the amount of water a family needs during peak usage periods(running dishwasher, sprinklers, and a shower at the same time). This usually is sufficient to support a family.
The last consideration is water quality. When purchasing or maintaining a property with a private water well, it is a good idea to get the water quality tested. This can reveal any contaminants that are a health risk, and also water contaminants that are not a health threat but which are aesthetic or even functional concerns such as color, sediment, water hardness, or water odors.
Much of the ground water in the GLWQD is considered hard because it contains a high proportion of calcium and magnesium. The hardness of water is expressed as a percentage of calcium carbonate, which is the principle constituent of limestone. Water is considered soft if it contains 0 to 60 mg/L of hardness, moderately hard if it contains from 61 to 120 mg/L, hard between 121 to 180 mg/L of hardness, and very hard if more than 180 mg/L of hardness. Hardness of ground water of the GLWQD ranges between 6 to 340 mg/L.
If you intend to use 35 gpm or less, and are not in a Controlled Ground Water Area, you are not required to obtain a permit, but you must file a “Notice of Completion of Groundwater Development” (Form 602) with DNRC within 60 days after you begin using the water.
If you intend to use more than 35 gallons of water per minute or 10 acre-feet in volume per year, you will need to apply for a “Beneficial Water Use Permit” (Form 600) from the DNRC in order to legally use the water in the well.
10 acre-feet is equilavent to 3,258,514 gallons of water. To put this in perspective, a single well operating within the 35 gpm and 10 acre-feet restrictions can support 90 – 178 people consuming average household water amounts.
Wells are allowed within the City limits for irrigation purposes only. The well cannot be connected to your household water distribution system. Under no circumstances can the well be used to supplement or replace water supplied by the City of Bozeman.
Category : Bozeman Information