The best way of preventing algae formation within your water softener system is to take away the primary source of the contamination by treating it with chlorine or placing a filter in front of your water softener.

Although algae growth can be reduced by removing catalysts like standing water, heat, and light, if the source is left untreated the algae are likely to return over time.

Main Sources Of Algae In Your Water Softener Salt Tank

It is important to realize that, although they might look like algae, the most common infestations found with water softener systems are actually caused by bacteria.

Unfortunately, bacteria are basically everywhere, which can make them very difficult to treat.

Whether your water is from a local well or supplied by your city, most water will contain some bacteria, that is why in some places city water contains added chlorine to kill off the bacteria.

Whether or not you suffer from bacteria growth in your water softener system often depends on whether your water contains any other contaminants, like iron, that bacteria can use as a source of energy.

Although most likely no water source will ever be fully free of bacteria, luckily the most commonly found bacteria have no negative health impact.

Caution: If you are unsure about the source of a contamination consult an expert as in rare cases there could be potential health risks.

Most Common Types Of Infestations

As mentioned the most common types of 'algae' in water softeners are actually bacteria, mainly the 'Sulfate-reducing bacteria' and the 'Iron- or Manganese-reducing bacteria'.

Luckily none of these are harmful to your health, however, they can have other unpleasant side effects like discoloration of the water and/or clothing or giving off a nasty smell.

Sulfate-reducing Bacteria

This bacteria lives off sulfate and is therefore mainly found in areas with sulfate-rich water. The presence of these bacteria can often be recognized by a foul rotten egg-like smell given off by the water.

Sulfate-reducing bacteria form as a dark slime throughout your house, and can often be found in standing water like the water tank of your toilet.

Although they are not harmful to your health they can clog up pipes and other appliances thereby reducing or completely stopping the water flow.

IndicatorsRelated issues
Dark slime in salt tankClogged pipes
Rotten egg smell

Iron- And Manganese-reducing Or Oxidizing Bacteria

As the name suggests, these bacteria generate energy by oxidizing iron molecules within the water and are thus often found in areas with iron-rich water.

As the iron is oxidized it precipitates from the water thereby reducing the concentration of iron and manganese within the water.

As the iron precipitates, it can end up on the bottom of your salt tank, water boiler, or within your pipes. Too much build-up of these particles could eventually start damaging or clogging up your water softener or other appliances.

IndicatorsRelated issues
Brown sludge in salt tankClogged water softener system
(Brown) foamy layer on top of standing waterOxidation within appliances
Brown/Rust-colored water

The formation of a brown sludge at the bottom of your brine tank should not be confused with salt mushing which results in a similar effect as salt crystallizes and gathers at the bottom of the tank.

What Causes Algae Or Bacteria To Grow In Your Water Softener System?

Algae generate energy through photosynthesis and thus need light in order to grow, therefore it is best to use a water softener system that has opaque brine and resin tanks. These tanks often contain standing water and are therefore more susceptible to algae growth.

However, as mentioned, the most common infestations are caused by bacteria, their growth is not dependent on the presence of sunlight but other energy sources like iron, sulfate, or heat.

Both algae and bacteria tend to grow faster in warmer environments, so keeping your system in the shade, or installing it in colder environments like a basement reduces the risk of growth.

Regardless of where your system is installed make sure the drain lines and piping from and towards your system are opaque to avoid any direct sunlight.

Growth is also accelerated in standing water, for example within a system that is not used over prolonged periods, or in other water treatment systems like a water filter that can contain large water tanks.

Preventing Algae And Bacteria Growth

The only way of permanently preventing the growth of algae and bacteria is treating the contamination at the source, like a well or water tank.

Treat At The Source Or As Close As Possible

The easiest and most effective way is adding chlorine bleach, this can be done at the source, for example in a well, or at the point of entry, where the water enters your home, through the use of a water filter system that uses a chlorine cycle.

Around a quarter of a teaspoon of bleach per gallon of water should do the trick. Be sure not to add too much as this could harm your water softener or other appliances.

If you are using the water for consumption you might want to consider adding a chlorine filter to remove the strong chlorine taste. Be sure to use unscented bleach and follow these other guidelines.

In the case of iron-oxidizing bacteria an iron filter could help, but be sure to use one that includes a step to kill bacteria so they are not able to contaminate your house.

Remove Other Growth Catalysts

Unfortunately, it isn't always possible to fully remove the source of the contamination. In such cases, it is important to prevent algae or bacterial infestations from growing in your water softener system by removing any growth enhancers as much as possible.

  • Prevent direct sunlight - Direct sunlight introduces the possibility of photosynthesis and brings along heat. Make sure your water softener system and all other water piping are located in the shadow when possible and are opaque.

  • Avoid warmer environments - If you live in warmer climates this is of course harder but then you could still consider moving your water softener to a basement or another relatively colder part of your home.

  • Prevent air contamination - Keep everything sealed off from the outside to avoid any outside contaminations

  • Reduce standing water - Avoid using large tanks where possible. If you don't use your system during winter times make sure it is winter-ready.

How To Get Rid Of Existing Infestations

When you've taken all precautions to prevent new infestations, or you suspect the source of the contamination is no longer present it is time to clean out your system.

It is important to thoroughly clean everything to prevent the infestation from coming back within a couple of weeks or even days.

How To Remove Algae Or Bacterial Growth From Your Water Softener System

  • Step 0. - Turn on your bypass and turn of the system.

  • Step 1. - Clean out the salt tank and scrub it clean using bleach. Reattach and disable the bypass.

  • Step 2. - Add chlorine to the salt tank and manually do a backwash. 1/4 teaspoon per gallon of water.

  • Step 3. - Perform 1-2 backwashes without chlorine to remove any residue

  • Step 4. (optional) - Use a resin cleaner according to instructions.

  • Step 5. - Fill up your tank with the right amount of salt and start using your system.

Caution: Be sure not to mix the bleach with salt or resin cleaner as these might react and cause toxic fumes.

Prolonged exposure to high concentrations of chlorine can permanently damage your water softener resin while also releasing poisonous gases. Be sure to check your system's manual regarding the usage of bleach in combination with the system.

If bleach is not an option you could consider using hydrogen peroxide or replacing your systems resin with a new and clean one (be sure to do this after disinfecting the rest of the system so the new resin is not immediately contaminated).

Some resin can get damaged by aggressive cleaning and might need to be replaced. Certainly, if algae have been around for long this is a possibility.

Remove Infestations From Home Plumbing

After taking the right precautions it is important to fully clean and flush your whole house system with bleach, chlorine, or something else, to get rid of all the algae.

This can be done by adding chlorine to your water supply and run your taps and appliances until you smell a slight whiff of chlorine and closing them again.

Leave the pipes filled with chlorine for a few hours. Run through freshwater to clean out the growth residue as well as rinse away the chlorine taste or smell.