What causes black sediments in well water?

I’ll try to explain what causes black sediments in the well water, and how to get rid of them. Anyone who uses a private well for domestic water knows what are the black sediments, but not everybody knows how to remove those. It isn’t rare to find black sediment in water from time to time. However, it is good to know how to stop black sediments from appearing in the future.

well water black sediments and sand
Well water

The black mineral in the water makes it rusty and tasting not so good. This mineral in the water could course the staining of faucets.

The acceptable manganese presence in water in the United States is 50ug/l. According to the Environmental Protection Agency (U.S. EPA), keeping manganese below 50 ug/l prevents the adverse effects of staining home faucets.

What causes black sediments in well water?

Sediments like manganese, sand, silt, grit, or rust are caused by one of the following: low water table, wrongly placed pump, faulty filters.

To avoid black sediments appearing in the water, make sure you have an appropriate water filter, pump installed properly and all water hoses are in good condition.

Choose an appropriate water installation, depending on your residential needs and family number members.

However, sometimes a mineral deposit can be disposed into a water aquifer through a natural erosion process. This occurs when the walls of the aquifer collapse into the water. Sediments dropping into the water could be seen as rust in the water.

Besides all I wrote, another natural process can lead to the rusty color of drinking water. In the case of nearby floods, the erosion process can trigger sediments to be deposited in underground water. Although most minerals are filtered out, some will find their way into your tap especially in case filters malfunction.

What are the effects of exposure to manganese on your health?

Exposure to manganese isn’t harmless. In the case of manganese exposure, a human can feel malfunctioning of the nervous system which results in a disease that looks like Parkinson’s.

In addition, infants tend to absorb more manganese than adults. Manganese affects learning ability in children.

While some sediment has adverse health consequences, most sediments are not harmful. Sediments that come with disease-causing microorganisms such as bacteria and viruses lead to diseases.

According to U.S. EPA (U.S. Environmental Protection Agency), if sediments are accompanied by an unpleasant odor, you should have your water tested for contaminants.

If you have sand in your drinking water, that indicates a high concentration of sand in the well or the pump is too strong for the well you own. Sand in water might indicate that the well is filled with sand or the pump is too strong. Sometimes the pump isn’t too strong, rather it is installed too deep in the well. A simple solution for a wrongly placed pump is to move the pump from the well bottom.

What to do when you have black sediments in your water?

  • Check if water has unpleasant odor or a bad taste
  • Install a whole house water filter
  • Change the pipes
  • Move the pump from the well bottom

How to remove sand in well?

Like I wrote before if you see sand in your water first try to move your water pump from the bottom. It is important to lift the pump higher, away from the floor of the well where sand deposits. Hire a specialist to install a water pump instead of DIY.

Another way to get rid of sand from the well is to install a special separator. It is usually placed between the pump and the pressure tank on the ground. This device is designed to spin the water on a way to the pressure tank. That movement settles the sand at the bottom inside the separator, and the water goes into the pressure tank.

Sand in well water causes

The unusual and sudden appearance of sand in water could have been triggered by several things. In most cases, a sudden sand appearance in the well water could indicate that yours well is filling up with sand.

well drilling
Well drilling image source

A primary source of sand in the well is gravel parts on the inner edge of the well. When the well is being drilled its inner edge was coated with iron to act as a protective layer to keep sand out. Once that protective layer has been damaged, nothing keeps sand away from the water.

Another reason sand appears in the water is that the water pump isn’t installed properly. A water pump should be placed at about 15 feet above the base of the well. If the pump is set to close to the bottom of the well, suction power is mixing the sand with water, delivering contaminated water in the plumings. Therefore, sand in the well water could indicate that your pump is placed wrongly, too close to the floor.

Sometimes the water pump is just too powerful for the well you own. Try reducing the suction power, or install a new pump that is appropriate for the well.

Bacteria pressence in well water

Bacterias are always in our lives. Usually, we don’t worry about their presence, and in most cases, they are not harmful.

However, a large presence of bacteria in well water isn’t something we want. A significant number of bacterias and other living organisms in well water indicates that the water is contaminated with disease-causing microorganisms.

Sometimes the presence of bacteria in well water indicates that human waste could have infiltrated the well. Sewage or human waste gets through the soil into underground water when there is leakage in the sewer system, and it gets into the rivers and underground water.

In case you doubt the water quality: It is a good idea to do a bacteria-presence test. If it shows bacteria presence positive, you should boil the water before drinking it.

What about mud in well water?

mud in water
Mud in water

The presence of mud in well water usually indicates that the volume of water is down. The water volume occurs if the well is not deep enough, or the water level is down during dry periods. In case the water level is down, the pump is sucking dirt (mud) which is why you see mud in the water. To avoid mud appearing in the water try reducing water usage in the dry season. A long-term solution would be drilling well deeper than it is.

Sometimes well isn’t drilled properly and that is why mud appears. The presence of mad could indicate that the well was not properly drilled. If the well is drilled near the places which let water into the well, too high up on the ground, then the surface water which is mostly muddy shall go into the well.

A misplaced water pump that is too near the floor of the well might cause the mud to appear in the water. I suggest you call a plumber to check out the well.

Drilling a water well and problems that occure

I’m really not an expert, but I have some time to explore and see what are common problems with water wells. Drilling a water well is something professionals do, and we assume they know what they’re doing. Still, sometimes problems occur and these are reasons what is that.

Incorrect well construction: An example of an inappropriate construction is when the well is designed such that it allows water in high up the well instead of placing the protective layer at the correct depth. Also, installing a low-quality protective layer will result in the protection of letting in sands and other impurities into the water.

Over-pumping: In case a too strong pump is installed, it will result in dirty water being pumped.

Mineral infiltration: Mineral-like calcium, magnesium, and iron could infiltrate the well. Mineral penetration is most common in places where the water table is high on the ground.

Aquifer problems: Although most challenges for wells are a result of inappropriate construction, sometimes the problem could originate from the aquifer itself. Some aquifers are not able to recharge, or the rate of recharge is very low compared to the rate of water usage.


I hope you’ve learned something about well water, residential water installations, and water quality in general. In this post, I’ve focused on black sediments in well water, and it is time to make a conclusion.

Black sediments in well water indicate the presence of manganese. While a small amount of manganese is usually present in the water when it increases it appears as black sediments, minerals such as manganese, iron, calcium, and others can be deposited into the aquifers through a natural process.

To be sure that you’re drinking healthy water I suggest make a water test. For your own safety, and the safety of the whole family, it is important to make a water quality test on a regular basis. You should make water tested to see if the black sediments are accompanied by harmful bacteria.