Is Polyphosphate in Tap Water Safe for Kids?

Within the limits set by national standards, it is safe for children to drink water containing trace amounts of polyphosphates, but parents should consciously control and reduce their children's intake of them.

1. What are polyphosphates? Why are they in water?

Polyphosphates are a category of various phosphate polymers, commonly including sodium tripolyphosphate and sodium hexametaphosphate. In drinking water treatment, polyphosphates are widely used as corrosion inhibitors and scale inhibitors. Their main functions are:

• Preventing pipeline corrosion: They form a protective film on the inner wall of water pipes, reducing the dissolution of metals (like lead, copper) into the water.

• Preventing scale: They inhibit the scaling of minerals like calcium and magnesium, keeping pipes clear.
  Therefore, water treatment plants add trace amounts of polyphosphates to the finished drinking water. This is a permitted conventional water treatment process both internationally and domestically.

2. Safety and Regulatory Standards

• Chinese Standards: According to China's "Standards for Drinking Water Quality" (GB 5749-2022), there are relevant regulations limiting phosphates (calculated as phosphorus). The dosage added by water treatment plants is strictly controlled within this safe range. From this perspective, compliant tap water is safe.

• International Perspective: Organizations such as the World Health Organization (WHO) and the U.S. Environmental Protection Agency (EPA) also do not list phosphates in drinking water as strictly restricted toxic substances, because their primary risk lies not in acute toxicity, but in the potential health impacts possibly associated with long-term excessive intake.

3. Potential Risks and Concerns for Children

Even though it's safe within standards, why do children need special attention? The main reasons are as follows:

• Physical Development and Metabolic Differences:

• Children's kidney function is not fully developed, and their ability to excrete phosphorus is not as strong as that of adults.

• Children have lower body weight, meaning the relative dose they ingest per kilogram of body weight is higher.

• Potential Interference with Mineral Absorption:

• Excessive intake of phosphates can bind with minerals like calcium, magnesium, and zinc in the intestines, forming insoluble compounds that may affect the absorption and utilization of these important minerals. For children in the critical period of bone and teeth development, ensuring adequate calcium absorption is crucial.

• Potential Long-Term Health Risks (Debated, but Worth Attention):

• Some studies suggest that long-term excessive intake of phosphorus (whether from food or water) may be associated with bone health issues (such as increased risk of osteoporosis) and cardiovascular health problems. However, these studies mostly focus on total phosphorus intake, and the conclusions are not yet entirely consistent.

What is more noteworthy is that modern children already ingest significant amounts of phosphates from processed foods (like ham sausages, burgers, potato chips, certain beverages). If drinking water becomes an additional source, the total intake could potentially be high.

4. Suggestions for Parents

You don't need to panic about tap water, but you can adopt some better strategies to ensure your child's drinking water safety:

• Top Priority: Control Phosphates in the Diet

• This is the most crucial step. Minimize your child's consumption of processed foods containing high levels of phosphate additives. Check food ingredient labels frequently and be alert for terms like "sodium tripolyphosphate," "sodium hexametaphosphate," and "sodium pyrophosphate." Encourage children to eat more natural, unprocessed foods.

• Water Choices

• Boiling Tap Water: While boiling does not remove polyphosphates, it kills bacteria and promotes the precipitation of some temporary hardness as scale. It is a safe drinking method.

• Using Water Purifiers: If concerned about phosphates and other substances in water, consider installing a water purifier that uses Reverse Osmosis (RO) technology. RO membranes can efficiently remove ions from water, including phosphates, providing almost pure water. This is the most effective method for removing dissolved salts.

• Choosing Reliable Bottled Water: You can choose bottled water sourced from natural mineral water or purified drinking water, and check its composition table.

• Ensure Nutritional Balance

• Ensure your child's diet contains sufficient calcium, magnesium, and vitamin D (which promotes calcium absorption), obtained from sources like milk, soy products, and dark green leafy vegetables, to counteract the potential mineral absorption interference from phosphates.

In simple terms, the trace amounts of polyphosphates in drinking water are not the main issue; the high levels of additives in the diet are the source that requires more vigilance and control.