There are three main causes for black sand, material or sediment in well water: minerals such as iron oxide or manganese, clay particles from soil or mud, and organic matter such as plant roots or animal hair decomposing – all of which will sink through the water column when they reach the bottom of your well.
Other causes can be related to the upkeep of your well and plumbing system. For example, a collapsed well or old pipes could also be leaching black dirt into your water.
If you’re unsure what’s causing your problem, we recommend Tap Score’s Well Water Test Kits.
After you’ve tested your water, there are several ways to deal with the problem, depending on the cause. Some of the most common solutions are installing a water sediment filter or an iron & manganese filter. Or you may just need to fix a collapsed or broken well or replace rubber piping that has disintegrated.
What causes black sediment in well water?
Black sediment in well water is most likely caused by harmless natural minerals, but it can also be caused by mud, soil, or human waste.
Let’s explore these causes of black sediment in your well water system one at a time.
A brand new well
If your well is brand new then it’s totally normal to experience discolored, dirty water.
Black particles in your water may be a sign that you have a well that was properly drilled.
When a well is installed into a new area, the drill bits used to reach the groundwater often stir up minerals and sediment .
This can take several weeks to clear and is no cause for concern. In the meantime, you can buy bottled water.
A collapsed well
Collapsed wells or the ones left behind from inadequate filtration systems can lead to sediment and muddy water . This could be after heavy rain or an earthquake for example.
If you suspect that there’s black matter in your water because of a collapsed well, then hire a local contractor to test the water yourself before contacting your state regulatory agency. A collapse is usually repaired on an emergency basis which often costs more than usual.
Mineral deposits (hard water)
While these might look like sediment to you, these are actually dissolved metals. They’ll only turn back into solid matter after they have entered your plumbing system.
Water hardness usually means you’ll notice scale or crust on your plumbing, water heaters, faucets, and pressure tanks.
Some mineral deposits that can appear or be mistaken for black sediment include:
- calcium carbonate
Iron occurs naturally in rocks and soils, but if your well runs through a bed of iron-rich stone or soil, you may experience the side effect of rust-colored stains on sinks or laundry, as well as black particles and debris in your well water.
Manganese is also naturally occurring in rocks and soil, but it’s also an essential nutrient for humans and the nervous system. However, once manganese gets into your water it can cause a bitter or metallic taste and black particles and debris.
Black matter in water could also be caused by other minerals like calcium carbonate [Wikipedia]. This is the most common black contaminant found in water, and it’s not harmful at all. Calcium carbonate may look like tiny pieces of gravel or chalk, and it is actually a mineral deposit left from groundwater that has been exposed to limestone or dolomite rock.
Sand and silt
When water runs over rocks and soil it becomes discolored by the sand and silt. This will sink to the bottom of your well which can usually be seen at the end of a water test.
Sand can also be taken in by a wrongly placed pump, or a very powerful pump that is too strong for purpose.
This is unlikely to be harmful to drink, but it does lower water quality and taste. You may even notice that your water is kind of crunchy!
Mud and soil
If you have a well situated near a river, flood plain, or muddy area of land, fine sediment from the ground may have sifted into your water supply. This is usually a nuisance but is not likely to cause any health problems.
Organic matter that finds its way into your well often finds the bottom of your well – where it decomposes and causes black debris in your water. If you suspect this is occurring it will be easy for you to identify because when organic matter decomposes, there is a long stringy buildup in your pump basket and an unpleasant odor in your water pipes.
This type of sedimentation gets worse over time and may eventually clog up the pump or feed pipe to your house or cabin increasing pressure in these parts and increasing the need for repairs when something begins breaking down.
Sewage or other types of human waste
If you have a septic tank or other system for treating sewage from your home, black material may appear in the water as a result of a backup in the system releasing effluent into the soil near your well.
If you find that the black color in your well water is caused by human waste, there are some steps you can take to address the problem. You should act immediately because human waste in well water usually contains dangerous pathogens and harmful bacteria .
First, let’s make sure this is a problem with your septic system – not simply mud or soil around your well. If it turns out that human waste is the culprit, contact a local contractor specializing in repairs for septic systems for an assessment of whether or not repairs are needed.
If necessary, have your septic tank cleaned and then re-sealed to ensure there are no leaks into the surrounding area where your well draws water from.
Rubber from a water heater or other appliance
If you have a water heater or another appliance that has rubber pipes, it can occasionally release small amounts of black material into your water. This is due to the rubber being eroded or decomposing.
Black sediment-like substances in your toilet bowl can be caused by a disintegrated toilet float.
What can I do about black sediment in well water?
Fortunately, there are several things you can try to minimize problems with these contaminants: If iron is causing your brown stains and bad-tasting water, modern filter systems can remove both manganese and iron from your drinking water without removing beneficial minerals like calcium. You should also keep an eye on the pH level of your water because low pH can encourage corrosion of metal pipes leading from wells.
1. Fix failing septic tanks and replace old pipes and hoses
If a septic backup is to blame, then this is the first thing you should do to address black sediment in water that is caused by human waste.
And if your septic tank has never been opened before, having everything professionally pumped out and cleaning the tank may be best to address this problem.
If an old rubber hose or rusted pipes are the cause of the dark sediment in your water, then get these replaced.
2. Get your water tested
If you’re still suffering from dark sediment in your water, the next step should be to get your water tested to find out exactly what is causing the problem.
3. Install a sediment filter and or sand separator as a pre-filter
Sediment filters remove black sediment in well water very effectively. They work by trapping the fine particles of sediment that cause staining and odor. They can even remove small amounts of metals in your well water to a certain extent, which will prevent them from entering the rest of the plumbing system.
The best sediment filters for well water are spin-down filters which use a special screen (also known as a mesh) to trap the sediment particles as water flows down.
We reviewed five different systems and found the iSpring WSP50ARB to be the best overall sediment filter for well water.
Home Water Research Recommends
Best Overall Sediment Filter for Well Water
- Convenient auto-flush module
- Easy-to-use touchscreen
- 50 and 100-micron options are available
- Easy installation
- Low maintenance
If the main problem is sand in your water, you may want to invest in a sand separator instead. These are installed between your well pump and the pressure tank. The design of the separator will depend on your specific situation, but basically, it stops sand from entering the bottom part of the well where the pump is located.
4. Buy a manganese or iron filter for well water
If your black sediment-water is caused by manganese then you may want to consider a greensand manganese filter for well water. These types of filters are activated by water flowing over greensand (granular ferric oxide). As the manganese in your well water passes through the filter, it is oxidized into a form that won’t cause black sediment or bad-tasting water.
The best iron filters for wells use chemical injection to do the same thing, but this can be very expensive. This involves using hydrogen peroxide to oxidize the manganese into a form that won’t cause black sediment or bad-tasting water.
Iron filters require regular maintenance and chemical treatments to get the most out of them, so they may not be worth the extra headache for you if your well water has high levels of manganese in it. Sand filters are another good way to remove brown stains and yellow staining caused by iron contamination…the key is to find a filter with very fine sand grains – otherwise, it won’t be able to remove the particles from your well water effectively.
5. Get a water softener for hard water or excess minerals
If the dark-colored matter in your water is caused by high levels of minerals like calcium or magnesium, then you may want to consider treating your water for this specific problem.
Hard water will cause scaling on the inside of metal pipes which can lead to rusting and corrosion. It can also make it harder to clean sinks, tubs, and toilets. It can even leave spots on glass shower doors if not treated properly. The good news is that hard water problems are easily solved with a water softener.
Many types of water softeners work by removing the calcium and magnesium from your well water using an ion exchange process (similar to how modern dishwashers soften tap water).
Black sediment in water is a common problem that can be solved with the right type of filter.
If you are experiencing black sediment in your well water, have it tested to find out exactly what is causing the problem and then install one or more filters for this specific issue.