How To Quickly Get Rid Of Algae From Well Water


Around 15% of all households in America use well water, and at some point these wells will have algae growing in the water. Thankfully, getting rid of algae from your well water is actually a lot easier than you may think.

Shock chlorination will effectively remove algae from well water. Purge the well before adding a chlorine bleach and water solution to the well, allowing the solution to sit for at least 12 hours before again purging the well. Regular doses of chlorine will also prevent future algal growths or blooms from establishing in your well

Before you go ahead and add chlorine to your well be sure to read this article, which has everything you need to know about algae growths in your well, including:

  • How to get rid of algae from your well (a step-by-step guide)
  • What are algae?
  • What causes algae to grow in your well?

How to get rid of algae from your well

A major challenge for most well owners is that they are prone to developing algae. When this happens, the water is unsuitable for drinking.

Thankfully, getting rid of algae from your well water is straightforward, simply follow this step-by-step guide to treat your well water with chlorine and disinfect your well:

1. If you have a pump, use it to purge your well – you want to purge 3 well volumes if possible. If you don’t have a pump you can bail water from your well with a bucket.

2. Close any valves to water softeners or water purification devices that are attached to the well

3. Add an appropriate amount of chlorine bleach to your well. The Centers for Disease Control and Prevention (CDC) have great information on how much chlorine you need for the safe cleansing of your well.

See the tables below for this information and to figure out how much chlorine you need to mix with water for your individual well. Just use the depth of water in your well and the diameter of your well to work it out.

Ultimately, you are trying to reach a chlorine concentration of > 100 mg/L. Once you know the amount of chlorine you will need, keep reading for the next steps on HOW to get rid of the algae.

Depth of well water: 10 feet

Diameter of wellChlorine bleachWater
0.5 foot1/2 cup3 – 5 gal
1 foot1 3/4 cups 3 – 5 gal
2 feet7 cups3 – 5 gal
3 feet1 gal3 – 5 gal
4 feet1 3/4 gal3 – 5 gal
5 feet2 3/4 gal3 – 5 gal

Depth of well water: 20 feet

Diameter of wellChlorine bleachWater
0.5 foot1 cup3 – 5 gal
1 foot3 1/2 cups3 – 5 gal
2 feet14 cups3 – 5 gal
3 feet2 gal3 – 5 gal
4 feet3 1/2 gal3 – 5 gal
5 feet5 1/2 gal3 – 5 gal

Depth of well water: 30 feet

Diameter of wellChlorine bleachWater
0.5 foot1 1/2 cups3 – 5 gal
1 foot5 1/4 cups3 – 5 gal
2 feet1 1/4 gal3 – 5 gal
3 feet3 gal3 – 5 gal
4 feet5 1/4 gal3 – 5 gal
5 feet8 1/4 gal3 – 5 gal

Depth of well water: 40 feet

Diameter of wellChlorine bleachWater
0.5 foot2 cups3 – 5 gal
1 foot7 cups3 – 5 gal
2 feet1 3/4 gal3 – 5 gal
3 feet4 gal3 – 5 gal
4 feet7 gal3 – 5 gal
5 feet11 gal3 – 5 gal

Depth of well water: 50 feet

Diameter of wellChlorine bleachWater
0.5 foot2 1/2 cups3 – 5 gal
1 foot8 3/4 cups3 – 5 gal
2 feet2 1/4 gal3 – 5 gal
3 feet5 gal3 – 5 gal
4 feet8 3/4 gal3 – 5 gal
5 feet13 3/4 gal3 – 5 gal

4. Mix the chlorine bleach with 3-5 gallons of water (or 12-19 liters) BEFORE you add it to your well

5. Use a clean hose to run water back into the well, try to circulate the water if you can to help mix the chlorine around the entire well. You can also use a bucket to pour water back in, for thorough mixing.

6. Rinse the well casing with a hose or bucket for at least 10 minutes – this will help remove any chlorine from inside the casing

7. Turn ON all faucets inside and outside the home and run the water until you can smell the chlorine – it has a strong smell!

8. Turn OFF all faucets and leave the chlorine bleach solution in the well and household plumbing for at least half a day (or 12 hours) – this will not only remove the algae from your well but also any green slime or contaminants from inside your pipes

9. Use a hose to drain the chlorinated water onto a safe outdoor area – somewhere without plants or vegetation (as the chlorine will kill them!). Also avoid draining the water into any nearby water sources, such as rivers or lakes. Be sure to drain the water until you can no longer smell any chlorine. 

10. Turn ON all of the faucets in the home, letting the water drain until you can no longer smell chlorine. 

11. For the next day or so you should consider boiling your water (for 1 minute) before drinking it – just to be extra sure that all of the chlorine is gone!

Other Considerations

  • Remember to bypass ALL water treatment equipment to prevent any damage to the system during the chlorination event – this is generally achieved by turning all valves off; each system will vary slightly
  • Liquid chlorine solutions deteriorate over time, so always use newly purchased chlorine bleach to effectively and safely remove algae from your well water
  • Always use unscented chlorine bleach
  • If you are not comfortable handling the removal of algae from your well by yourself, you should reach out to a licensed well contractor or water professional. The Water Systems Council has a great list of licensed well contractors across the entire of the U.S. If you are not familiar with them, and are searching for a licensed water professional you can access their site via this link

Now that you know how to remove the algae from your well water, it is a good idea to know what type of algae there are and which type you are dealing with.

There are many different types of algae, and the conditions that they thrive in can vary. Determining what kind of algae you are dealing with may help you identify the best way to treat the algae in the long-term.  

If you can, take a sample of the algae to a local water treatment plant or send it to a certified lab for accurate identification. Once the algae are properly identified, you can move on to removing the growth. 

Obviously, identifying the type of algae you have in your well is in an ideal world, and testing water can become expensive. So, if testing your algae from your well isn’t an option – DON’T WORRY! The vast majority of algae respond to the same treatment (shock chlorination), as outlined in the above steps.

What are algae?

Algae are tiny (microscopic) or large (macroscopic), plant-like bacteria that are known for naturally occurring in bodies of water, like ponds, lakes, rivers, and streams. Algae can have amazing colors, ranging from blue-green to olive-green and even red.

There are a huge variety of algae, but there are 4 main types that tend to affect well water:

  1. Green algae (chlorophyta)
  2. Blue-green algae (cyanobacteria)
  3. Brown algae (diatoms or bacillariophyta)
  4. Red algae (Rhodophyta)

Although algae are often not visible to the human eye, they can quickly develop into massive populations and form a big mass that is referred to as a bloom. However, this development only happens under favorable conditions.

Blooms usually develop late in the summer and early into the fall season. 

Depending on the type of algae, a bloom can turn the water into a bluish-green color, or give the water a turquoise paint or green pea soup look. Sometimes, these blooms can get so dense that they start to form solid-looking clumps. 

Fresh algae blooms usually smell like recently mown grass, but older blooms usually have a pungent, rotting garbage smell. 

Algae don’t just cause discoloration of your water or a build up of scum and bad odors, but can also have toxic effects for anyone that drinks the water.

What causes algae in wells?

Algal growths form in well water because the water is still, not enclosed and warm, and frequently contains excess nutrients, such as nitrogen and phosphorus. 

Too much nitrogen and phosphorus in well water can also occur if the well is located near agricultural areas. 

Increases in water temperature, high pH levels (alkaline water), or stagnant water can also cause algae to grow in wells.

Under these favorable conditions, the likelihood of having to deal with algal blooms also increases.

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