Water Wells

Few of the residences in the Perry Park area are served by wells, but as you get into more rural areas of Larkspur wells become more common. To the uninitiated who associate wells with farm life, this may seem like taking country living to the limit. But today’s wells are engineered to provide years of trouble-free service with minimal maintenance. In fact, there are so few maintenance costs that we consider wells a cost savings by comparison to municipal water utilities that charge $100/month or more. And the icing on the cake is that well-water users uniformly report that their water tastes better than municipal water!

Wells—water supply


The typical water well consists of a drilled borehole, 8-10 inches in diameter at the top and narrowing to 6 inches at the bottom. The hole is lined with a steel casing for the first 20 feet or to solid bedrock and plastic pipe then extends to the bottom. A cement and water mixture (grout) is poured between the upper casing and the side of the borehole to prevent shallow groundwater from entering the well. A submersible pump is located above the bottom of the hole, inside the plastic pipe. The water line to the dwelling is buried at least 6 feet deep to keep it below frost line in winter. The only portion of the well that is usually visible is the top of the steel casing with the cap bolted to it.

Well depths may vary from 50 feet to over 1,000 feet; it is possible for well holes drilled within 25 feet of each other to tap into different veins and produce significantly different yields. Well yields vary from 0.5 gpm (gallons per minute) to over 30 gpm. If a deep well has a low yield, it may be considered quite adequate because water stored in the bore of the hole (approximately 1 gallon per foot of well bore hole) will provide water for the family during peak usage times (mornings and evenings), while the well replenishes the storage 24 hours a day. Even where a shallow well yields relatively little water, a 200-500 gallon tank may be installed to provide storage for high-use periods and render the water system viable.

Water well contractors suggest that people use approximately 75 to 100 gallons of water per day in the following ways:

Bath: 37 gallons
Shower: 20 gallons
Toilet: 6 gallons
Dish washer : 14 gallons
Laundry : 40 gallons

A dripping faucet can use over 12 gallons a day and a leaking toilet may waste as much as 60 gallons a day.

We turn to licensed contractors to test the well as part of the due diligence in buying a home to determine whether the combination of well yield and storage capacity will provide adequate water to the household.

Wells—water quality


In addition to testing a well for water production, we recommend our buyer clients test the quality of the water as well. The test typically examines total coliforms, a group of related bacteria commonly found in water and soil. The vast majority of coliform bacteria do not cause disease, but if coliform bacteria are found in water, other disease-causing bacteria and viruses that are more difficult to detect may also be present.

The test also examines nitrate levels. While small amounts of nitrates are present in virtually all individual water supplies, higher levels of nitrates may pose a health concern and it would be appropriate to request the seller to add a water purification system before accepting the quality of water as satisfactory. Other less frequently tested aspects of water quality include fluoride, hardness and radon.

Again, we suggest our buyer clients use a licensed contractor to sample the water quality. The same contractors that test well yield can perform this test.