A question we often get asked is; what is the difference between a well and a water borehole?
Any type of well or borehole works by extracting water from an underground source found beneath the permeable rock. Water is naturally filtered through small fishers within the rock, reducing the presence of sediment and contaminants. This means that, with the right structure and lining, it can be used as a reliable source of drinking water.
Wells are especially common in third-world countries where access to fresh water is limited. Charities and NGOs will often fund installation in rural or urban communities in order to provide drinking and sanitation facilities for local people. However, this type of water source is becoming increasingly unreliable and so people are turning towards water boreholes for rural homes, farms, and leisure facilities as a way to reduce carbon footprint and save money long term.
Whilst it may seem like a well and a water borehole essentially do the same thing, there are some notable differences between the two.
What is a borehole?
A water borehole serves the same purpose as a well, to retrieve water from a natural source underground. This is installed slightly differently from a traditional well, using a large rotary drill that can penetrate much deeper into the ground. The cavity created from this technique is much narrower and deeper than a well, taking up less space and reaching a higher quality source of water which is then sealed out from any surface-level contamination.
What is a well?
A well is a traditional method of sourcing water from underground. Most commonly formed by hand, a shovel would be used to dig down into the ground until water is reached. A structure would then be built using bricks or rocks to leave an open hole and prevent the well from collapsing.
Traditional wells, particularly those built in third-world countries, would use a pulley rope to lower a bucket into the well to collect water and then slowly bring it up to retrieve the supply. In modern well structures and installations, a large pipe is used as a structure with a pump to supply water into a building.
Types of Boreholes.
1.Dug wells
Hand dug wells and other manual methods to dig a well have been in existence for thousands of years. Though mechanized methods are more efficient and effective, there are often no options for people and communities in need of water.
Manual Methods Used to Dig a Water Well
People have been making wells without the use of power equipment for thousands of years. Each of the methods described in this section involve hard work, but most can be carried out using locally-available materials and skills.
Hand-Digging.
Digging a well by hand, using simple tools like a pick and shovel, with a bucket on a rope to remove cuttings, is the oldest and probably the most frequently-used method of getting access to groundwater.
Advantages:
Making hand dug wells requires only common tools and skills, so it can be done by anyone. In many areas men have specialized in this trade as a business.
Where labor costs are low, this is usually the least costly method of well construction. In an aquifer with low permeability, a large diameter hand dug wells may produce more water than a borehole in the same aquifer.
Disadvantages:
Hand digging a well is very dangerous due to the high potential for cave-ins and lack of oxygen. Digging a well is very hard work for one person. Because it is difficult to dig very deep, hand-dug wells more than 30 meters are uncommon.
2. Driven Wells
A driven or sand-point well is constructed by driving a narrow pipe into shallow water-bearing gravel or sand. To create a driven well, a steel pipe with a diameter of 1¼ inches to 2 inches is driven into the ground. At the bottom of this pipe is a filtration screen attached to a hardened steel tip.
Once the first length of pipe, with the steel tip, is driven into the ground, additional lengths are added until the first pipe hits an aquifer.
To make the process easier, a pilot hole is sometimes dug at the surface using an augur or post-hole digger. The drive port and well screen are then driven into the ground along with the first length of pipe.
A drive cap can be used to protect the well points and drive pipe threads during the construction process. This is particularly important if you’re using a weighted driving tool or “slam hammer.”
A driven well can only be constructed in a location where the geology and groundwater supply make it feasible. That means identifying an area of sand or gravel where the water table is less than 50 feet deep.
The best way of doing this is by consulting geologic maps and surveys of your local area. You also need to establish if there is water available, which you can do by referring to the construction logs of nearby wells, or by consulting a geologist.
Water dousing or divination can also help you find the best place to sink your well.
The ideal location for a driven well is higher than the surrounding groundwater and has good drainage. This will reduce the potential for contamination. You should also identify any possible sources of contamination, such as areas where fertilizer is used intensively or where subsurface sewage seepage systems are in place.
Drilled Wells
Drilled wells or boreholes are the most common wells and the deepest. The average household drilled well is between 100 and 800 feet deep, but there are a few over 1,000.
A drilled well is constructed using a drill rig that bores into the ground 20 feet at a time. The first drill rods must pass through the overburden of dirt, rock, clay, and other material that sits on top of the bedrock.
Once the first 20 feet have been drilled, the next drill rod is added. This process continues until the drill hits water.
At the same time as drilling through the ground, the drill rig advances the well casing into the bored hole. This casing is usually around 6 inches wide and prevents dirt and other material from seeping into the well and contaminating the water.
As the casing is narrower than the bored hole, the space around it must be sealed using either cement or bentonite clay. Without this sealant, the water inside the well could become contaminated by water draining down from the surface around the outside of the casing.
We had a drilled well, or borehole, installed a decade ago, and it’s still going strong, producing a yield of around. 14,000 liters per hour.
Why opt for a water borehole…
Constant supply
Due to the deeper penetration into the ground, a water borehole provides a consistent, reliable source of water; even in drought conditions. Although a well retrieves water using a similar method, the shallower depth means that the aquifers can often dry up when used at a faster rate than replenishment.
A perforated casing that lines the borehole is what allows water to come through. The deeper the borehole, the more casing is needed and the more water is able to pass through. The size of your property and the amount of water you expect to use will determine the depth. Up to 20, 000 liters of water a day can be supplied via a water borehole if necessary with no licenses required. If you are a high-water user then hydrogeological reports can be commissioned to ensure the viability of a borehole based on your exact requirements.
Better filtering
Natural aquifers struggle to filter water completely and due to an increase in the use of chemicals in farming and agriculture, toxins from pesticides and fertilizers are making their way into underground water sources. In order for this water to not be contaminated and potentially harmful when consumed, an effective filtration and sterilization system needs to be in place.
At Hydrotech Drilling, we use submersible pumps, cartridge filter systems, and UV sterilizers to ensure our customers always have safe, clean water going into their homes or business. Should any contaminants be found in the water such as Iron or Manganese then we are able to design, supply and install additional treatment.
Hydrotech Drilling also seals the borehole using bentonite and a custom-fabricated wellhead in order to prevent any surface contamination and maintain high quality.
Discreet
Once installed, a water borehole is typically covered with a flat manhole cover which can be walked and driven over so it won’t affect your property or day to day life.
A traditional well is more of an open structure that would need to be accessible. Other modern well structures will still have a pipe structure that sticks out of the ground.
Over time, water boreholes have overtaken traditional wells as a convenient, reliable source of clean water. The upfront installation costs can seem high but a return on investment is typically made within two to three years for high water users.Hydrotech Drilling are experts in water borehole installation. If you are interested in being more self-sufficient, reducing your impact on the environment and adding value to your property, do not hesitate to contact us www.hydrotechdrilling.co.zw and we will be happy to help.
