Phosphate In Water (Everything You Need To Know)

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Phosphate In Water Guide

Phosphate levels have been increasing over time which has rightfully caused concern about the effect on people’s health and the environment. Phosphates enter our drinking water from a variety of sources, both natural and manmade.

This article will cover what phosphate is, why it is added to our water supply, and what you can do to reduce exposure to the mineral.

Key Takeaways:

  • Phosphate is primarily added to drinking water by public treatment systems to prevent lead and copper contamination.
  • The EPA established a safe level of total phosphate in water at 0.1 mg/L for streams that do not discharge into a lake.
  • The best method to test for phosphorus in drinking water is with a certified lab test kit to get the exact concentration amount.
  • The best treatment method to remove phosphate in water is reverse osmosis or activated carbon filtration.

What Exactly Is Phosphorus?

Phosphorus is an essential mineral that is critical for the growth of bones, teeth, and plants. The phosphate ion PO₄⁻³ forms compounds containing this element. Elemental phosphates exist in three major forms: orthophosphate, polyphosphate, and organic phosphate.

Orthophosphate and polyphosphate are the two primary types used in the water treatment process. Orthophosphate is commonly used to prevent lead and copper from leaching into the water supply. Orthophosphate is available as phosphoric acid (H₃PO₄) and its salts sodium or potassium.

Polyphosphates treat water quality issues from inorganic minerals like iron, manganese, and calcium in groundwater, however, they are not effective at controlling lead and copper.

Lastly, organic phosphates play a critical role in nature. Their presence typically comes from the breakdown of organic pesticides or phosphorus-rich bedrock.

The terms phosphate and phosphorus are both used when discussing the presence of phosphate in water. Although often used interchangeably, they are not the same. Phosphorus is a non-metal element. It can be found in rocks as inorganic phosphates. Water can get phosphate in it as it runs over these rocks. Although leaching out of rocks is one-way phosphate enters the water stream, it is not the only way.

How Does Phosphate Get Into Water?

How Phosphate Gets Into Water

Phosphates can get into the water supply in a number of ways, but excess phosphorus can affect water quality. Here are some of the ways that phosphates can enter water systems.

  • Phosphorous rich bedrock
  • Phosphorous in fertilizer
  • Industrial waste
  • Phosphorous in human and animal waste
  • Water treatment additives

Why Is Phosphate Used in Water Treatment?

Zinc or sodium orthophosphates or phosphoric acid are often added to drinking water at public water systems as a corrosion inhibitor to prevent the leaching of lead and copper from pipes and fixtures.

The phosphate metal salt forms a protective coating of insoluble mineral scale on the inside of service lines and household plumbing as well as in commercial water applications and significantly reduces the leaching of those metals.

The ability of orthophosphate to control dissolved lead and copper depends on the concentration of phosphate, pH levels, and mineral composition of the water. 

Coagulation and filtration using iron salts are commonly applied to reduce phosphate levels in drinking water or wastewater.

What Are The Effects Of Phosphate In Drinking Water?

Phosphate In Water Sources

Phosphates in drinking water are typically safe for humans unless consumed at very high levels. However, elevate exposure to phosphate can lead to acute health issues.

Several studies show that ingesting high amounts of phosphate can have negative effects, such as digestive problems and an increased risk of cardiovascular and kidney disease. It should also be avoided by those with kidney disease who need to control serum phosphate. If you have or are at risk for certain health problems, the amount of phosphate in your water may be a bigger concern for you than others.

What Is the Acceptable Level for Phosphate in Water?

The Environmental Protection Agency (EPA) has established a recommended limit of 0.05 mg/L for total phosphates in streams that feed drinking water reservoirs and 0.1 mg/L for total phosphorus in streams that do not discharge into a reservoir.

Furthermore, data from the Water Quality Assessment project shows that the median total phosphorus concentrations exceed the suggested limit of 0.1 mg/L across most of the country.

Higher concentrations can pose human health risks and disrupt the water treatment coagulation process.

How To Test for Phosphate in Water

There are two methods you can use to test for phosphate in drinking water. These are certified laboratory testing or an at-home test kit. We will discuss both of these.

Certified Laboratory Testing

A certified laboratory test is the best choice for accurately determining the amount of phosphate in your water.

I recommend the Freshnss Labs water test kit which tests for phosphorus and dozens of other contaminants. It comes with everything you need to properly collect and sample and mail them to the lab to be analyzed. In three business days, you will receive a comprehensive report with the exact phosphate levels, and health or plumbing alerts, and the best treatment methods based on your lab data.

This is a great way to accurately and easily determine the phosphate levels in your water supply while receiving professional insight on any steps you need to take.

Laboratory Water Test Kit

Tests for phosphate, heavy metals, and dozens of other contaminants
Analyzed in a certified laboratory
Includes detailed report with EPA benchmarking and safety concerns

DIY Test Kit

Another method you could use for determining the amount of phosphorus in your water is a DIY test kit. Phosphorus can alter the chemistry of water and cause algae growth which can reduce oxygen levels in fish tanks, so aquarium owners often monitor the level of phosphates in their water. This means aquarium owners frequently choose to test their tank water’s phosphate levels. Because of this, kits for testing for phosphate in tap water are readily available in stores such as pet specialty shops or online.

Using these tests is easy. You simply dip the test strip into your tap water. Then, you wait for the strip to change color. The instructions will give the amount of time you should wait. Once the waiting time is complete, you compare the color of the test strip to the provided color chart. This should give you an idea of the amount of phosphate in your water. Although, it is not as accurate as a lab test.

What Is the Environmental Impact of Phosphate Dosing in Water?

Phosphates are often added to drinking water distribution systems. Yet, high levels of phosphorus can cause increased growth of aquatic plants in a water body, which can hurt aquatic ecosystems by causing lower levels of dissolved oxygen and, in some cases, algae blooms.

Although phosphate comes in many forms, it is commonly referred to as phosphate or PO₄ ⁻³ in natural bodies of water. Algae blooms are an overgrowth of algae in unproductive lakes that endangers all other life in its ecosystem–this is one great reason to be wary of excessive phosphates in a water system.

As a general rule, here are the total phosphorus concentrations for the trophic status of a lake:

  • Oligotrophic: < 0.01 mg/L Total Phosphorous
  • Mesotrophic: 0.01 – 0.03 mg/L Total Phosphorus
  • Eutrophic: > 0.03 mg/L Total Phosphorous

Phosphates become destructive as they fertilize aquatic plants and increase the natural eutrophication rate. This is also known as accelerated eutrophication or cultural eutrophication. Eutrophication is the natural aging process of a body of water. Accelerated eutrophication is an unnatural process where human activities speed up the natural process.

Over time, significant algae growth from phosphorus is associated with cyanobacteria toxins, bad odors, the death of aquatic animals, and poor recreational conditions.

How To Remove Phosphate From Water

Many people opt to filter their water for a variety of reasons, including the desire to decrease phosphate levels. There are several ways to remove phosphate from your water if you wish to decrease the amount your water contains, and we will discuss a couple of these below.

Activated Carbon

Activated carbon filters are one way to remove phosphates from your water. These filters remove most of the phosphates from the water. Charcoal carbon filters work particularly well, removing up to 90% of the phosphate from water. Activated carbon filters have the added advantage of removing other contaminants from water as well, such as heavy metals, pesticides, and chlorine, among others. In addition to this, carbon filters are very affordable. You may be able to find a water pitcher with a carbon filter for under $20.

Reverse Osmosis

Reverse osmosis is an even more effective method of removing phosphates from your drinking water. This treatment method can remove up to 98% of phosphates from your water. It will depend on the unit you purchase.

This method of filtration works by forcing water through a semi-permeable membrane, which blocks the contaminants from passing through, thus resulting in pure water as contaminants are held back by the filter. Reverse osmosis removes many other contaminants from water as well, such as heavy metals, microorganisms, and more.

Reverse Osmosis units cost more than those using carbon filtration. However, this method will generally remove more contaminants from your water. You can purchase these units for the countertop or under the sink. Weigh the benefits of greater purity versus the costs of the system you choose.


How much phosphate is safe in drinking water?

The EPA states that when natural reservoirs are used for drinking water, the level of phosphates must be kept at 0.1 ppm or less. Levels above this are not considered safe for drinking water. Although considering the long-term effects of phosphate in drinking water are unknown, some people may prefer not to have phosphate in their water, even at safe levels.

Does phosphate in water affect human health?

Phosphate affects human health considerably. At reasonable levels, it is an essential nutrient that is vital for healthy living. However, in excessive concentrations, it can cause fatigue, nausea, shortness of breath, and problems sleeping. These problems can have a great impact on quality of life and could aggravate other health problems.

Can a water filter remove phosphates?

Yes, water filters can remove up to 98% of all phosphates, establishing a strong level of purity and quality. Effective methods include activated carbon filters and reverse osmosis systems. These can be installed in a wide range of applications, including countertop or under-sink units.

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