There are more than 12 million homes around the United States that rely on a well for water. Wells are an important source of water as they provide water to people who live in areas where other drinking sources are not available, such as during a natural disaster or when the public drinking system gets contaminated.
Wells are more commonly found in rural areas since they’re an independent drinking water supply that does not rely on local infrastructure.
They’re also used by farmers for irrigation and also to feed livestock. However, to get water from a well, you need to first dig a well in the earth with tools like hand drills and shovels. But you can’t just dig a 1-meter deep hole and expect to get water. In this article, we will be touching on how deep should a well be for drinking water.
The type of well constructed will depend on your geology. A bedrock well is quite common and it consists of drilling deep into solid rock and tapping into the fissures that carry water. A typical household well is about 6 inches wide with a six-inch casing or liner.
A casing pipe is then installed down the shaft to the bottom of the well to keep surface water, sand, and other contaminants out of the groundwater.
Well construction will typically take about two days. The first day is spent on drilling the well depth and the second day is for installing the casing pipe and submersible pump.
However, determining the location of your well is extremely critical and it’s best to engage a contractor who is familiar with the hydrology and geology of your area. They should be experienced and equipped to know where’s the best place to drill and what would be a suitable system size. Not only that, but they should also be familiar with the codes and regulations for your location.
How to Estimate Well Depth
The cost of digging a well is based on how deep the well is. An experienced contractor who’s familiar with digging in your area will know the average well depth required to reach water and should be able to give you an accurate estimate of how much it’ll cost to deep your own private water well. As soon as adequate water supply is found, the drilling process can stop.
While a well contractor cannot tell you exactly how many feet deep they need to drill to reach water, they can make reasonable judgments based on the water quality and quantity from their previous experience.
You can also increase water yield by fracturing the bedrock immediately surrounding the well shaft via a process called hydrofracking. Pumping large quantities of water deep underground at high pressure will expose additional fissures in the bedrock, providing access to clean water.
The quality of your drinking water supply depends on several factors like geology and water levels. To reach maximum ground filtration to remove impurities and get better water quality, your well needs to be drilled deep – at least 100 feet deep. As a general rule, deeper wells will have more minerals present, and you may end up needing to install a water softening unit.
Problem with Shallow Wells
A well that’s less than 50 feet deep can be considered a shallow well. Wells with less than 100 feet depth will lack enough soil thickness to absorb all the contaminants seeping into the ground, and result in poor water quality.
Shallow wells extract water from the highest level of the water table, meaning you’re drawing water that’s more vulnerable to surface water contamination from sources like animal waste, motor oils, pesticides, and fertilizers. If you have shallow wells, make sure to get it tested at least once a year to ensure that your drinking water is still safe to consume.
Is Digging Deeper Better?
Digging deeper wells doesn’t necessarily mean you get better water quality. Not only that, but the deeper you drill, the more expensive it gets. Depending on the soil composition, a well can be built for as little as $5000, but could cost ten times more depending on how deep you want it to go and what you’re drilling through.
Shallow wells will produce higher yields while deeper wells need a larger pump system to draw water. This will also mean an increase in operating costs per year since they need to capture lower-quality water from further beneath the surface. The extra power needed to pump groundwater from greater depths will also mean an increase in your electricity bills.
Factors Affecting a Residential Water Well Depth
The main source of water in your well comes from underground aquifers which are pockets of water inside the bedrock. Therefore, your well needs to be deep enough to reach the aquifer to gain access to water. This means that the depth of your well will depend on how deep your aquifer is.
Typically, well needs to reach at least 300 to 500 feet deep – some may even reach 1,000 feet, to reach the bedrock. The depth of the water table can change throughout the year. For example, during late winter and spring when snow starts to melt or there’s more rain, the water on the surface infiltrates into the ground, causing the water table to rise. The water table then falls during hot, dry summers due to evapotranspiration.
The most reliable method to knowing the depth of the water able at any time is to measure the water level in a shallow well with tape. If there are now ells available, you can rely on surface geophysical methods by placing electric or acoustic probes.
Possibility of Surface Contamination
If you have a properly constructed well that’s installed deeper into the well, then you can trust that it is offers sufficient durability and protection. If you have a deeper well and more well casing, your water will take longer to reach the well pump from the aquifer. The longer traveling time not only means you need to wait a few more minutes, but it also means there’s a higher likelihood that any bacteria and harmful contaminant dies off or get trapped in the soil along the way, ultimately reducing the risk of contamination of the well’s surface water.
Another factor that could impact how deep your well needs to be is the geological characteristics of the bedrock below your house. The geology could impact the location of the aquifer, which then affects the depth of the well needed to draw water. Low yielding rock formations will require deeper well drilling for the well to act as a storage chamber for groundwater. The geology of the rock that needs to be drilled for the well will also determine the size and the depth of the well.
There are certain areas in the US that are “case off” where you are not allowed to drill wells to draw water due to poor water quality. In cases like this, you’ll need to dig an even deeper well to avoid these zones and avoid drinking from a water supply filled with harmful contamination.
This information can be obtained from your well driller/drilling company or local authority. In addition to that, you can also get information on the depth of the water table and ground water quality.
If you’re drilling deep for better water quality, make sure to also take into consideration the time factor. It takes a full day to get the well, cap and casing properly installed and an extra day just to install the well pump.
Water Table Fluctuations
As discussed earlier, the water table depth will fluctuate according to the season and you might need to drill your well deeper to anticipate these fluctuations. This will ensure that you always have access to groundwater supply, regardless of the water levels for the season. Information on water level and how it may be related to the diameter of nearby wells can be found online.
Different states will have different regulations on the well depth. Make sure to head to your local county health department to check on these specific guidelines and rules before drilling begins.
Generally, the well should have a casing that reaches 20 feet deep to reach the bedrock. You’ll then need to properly seal the outside of the well casing to stop sand and sediment from getting into your water supply.
You need to also remember that your well depth will affect a number of other drilling factors like cost, pump placement, well’s diameter, water level, and even water yield. A shallow well will cost less since it requires less drilling and less time.
Well Water Treatment
If you rely on private wells for your residential water, then it might be a good idea to consider getting a water treatment or filtration system to improve drinking water quality. These systems can help remove many contaminants that are commonly present in wells and could pose health concerns.
Some wells have hard water that contains minerals like calcium and magnesium. These minerals, although natural, can cause rashes and dry skin. Not only is this bad news for those with sensitive skin, but homeowners may also face scale buildup issues in their pipes, faucets, and water-based appliances at home. One of the best ways to overcome this is to install a water softener.
A water softener is a salt tank installed in your home’s plumbing that will “soften” hard water through an ion exchange process. It replaces hard ions like calcium and magnesium with sodium ions. This process will not only make the residential water feel better on your skin and hair, but it’ll also taste much better compared to hard water.
However, softened drinking water will have a higher sodium content which may be problematic for those with high blood pressure or kidney problems. Nonetheless, there are water softener options that do not use sodium available in the market.
Well Water Filters
Well water filters are designed to ensure your residential water and drinking water is clean and free of harmful contamination. A well water filter is made up of a series of filters that remove sediment, rust particles, and other contaminants.
The first layer of filter removes larger particulate matter like dirt or sand to about one micron size, the second filter removes finer particles like bacteria that are smaller than 0.04 micron. The series of filters will ensure that your drinking water is free of contaminants and safe for consumption.
UV purification uses ultraviolet light in a range of wavelengths to target and neutralize living organisms such as harmful bacteria and parasites. The UV light alters the microorganism’s DNA to prevent them from reproducing and eventually dying off. UV purification is an effective method to disinfect unsafe residential water.
However, you need to keep in mind that this system can only work effectively if the water is clear and free of precipitates. Cloudy water can interfere with the wavelengths and cause it to be less effective. This is why UV purification is usually set as the last step after other filtration methods to remove dead, invisible microorganisms that were small enough to pass through the filters.
Reverse Osmosis System
Another effective water treatment system is reverse osmosis. Reverse osmosis involves forcing water through a series of membranes at high pressure. The main star of reverse osmosis is the semi-permeable membrane that traps contaminants and only allows small water particles to go through.
This type of filtration is very effective and can remove up to 100% of organic material from water, including bacteria, sulfur, lead, dissolved iron, and other undesirable pollutants.
One disadvantage of this system is that it causes a lot of wastewater – about 20% of your water is drained off. Another thing to note is that the installation of a reverse osmosis system will likely require the help of a plumber as the system is not as simple to install.