Silica is one of the most common naturally occurring minerals on Earth, making it a frequent component of both well water and municipal drinking water. While it is not an EPA-recognized health concern in water, it can have other adverse effects if at high levels.

What Is Silica?

Silica is a naturally occurring compound found in rocks, sand, soil, and minerals. As groundwater moves through these materials, small amounts of dissolved silica may enter your drinking water.

Is Silica in Drinking Water Safe?

For most homeowners, yes.

Unlike contaminants such as lead, arsenic, or PFAS, silica is not regulated by the EPA as a health contaminant in drinking water. There is currently no federal Maximum Contaminant Level (MCL) because available research doesn’t show harmful health effects from silica in drinking water.

Some studies show that dissolved silica can benefit healthy bones and connective tissue at small levels.

Where Does Silica Come From?

Silica in drinking water is almost always naturally occurring. Common sources include:

• Groundwater flowing through sandstone, granite, quartz, and other silica-rich rocks
• Natural mineral deposits
• Surface water that has dissolved minerals from surrounding soil

Does Silica Affect Water Quality?

Although silica isn’t considered a health concern, it can create other problems around your home.

Higher silica levels can cause:

• White or cloudy mineral deposits on fixtures
• Scale buildup inside water heaters and plumbing
• Reduced efficiency of boilers and commercial equipment
• Spots on dishes and glassware after washing

It’s important to understand that these are not health issues but simply visual and financial.

How Much Silica Is Normal?

Silica concentrations vary widely depending on your region and water source.

Many drinking water supplies contain between 5 and 30 mg/L (ppm) of dissolved silica, although higher levels are common in some groundwater sources. There is no EPA drinking water standard establishing a maximum acceptable concentration.

Can Standard Water Filters Remove Silica?

Most common household water filters do not remove dissolved silica effectively.

This includes:

• Activated carbon filters
• Refrigerator filters
• Most pitcher filters

Removing dissolved silica typically requires specialized treatment methods such as:

• Reverse osmosis (partial removal)
• Deionization systems
• Specialized industrial treatment systems

The effectiveness depends on the form of silica present and the treatment technology being used.

Silica and Water Filter Effectiveness

Some people believe that you cannot filter water that has high silica content. This isn’t the case but it’s important for professionals to know your silica content before deciding on a filtration method. This is because silica can coat filtration media and lower the effectiveness and lifespan of your filter.

How to test for Silica

Testing for silica requires laboratory analysis. The Safe Home Premium Test Kit includes silica testing, along with many of the most important water quality parameters. If you are specifically concerned about residue on your appliances or dishes, or about the lifespan of your appliances, this kit can help. It also includes testing for hardness, TDS, the Aggressive Index, and LSI, all of which can contribute to these issues. Together, these results give you the information you need to identify and address the problem.

The Bottom Line

Silica is one of the most common naturally occurring minerals found in drinking water. While it can contribute to scale buildup and other aesthetic issues, it is not currently considered a health concern at the levels typically found in drinking water, and the EPA has not established a drinking water standard for silica.

If you’re interested in understanding the overall quality of your drinking water, comprehensive testing provides a much clearer picture than focusing on a single naturally occurring mineral. A complete water analysis can identify contaminants that may impact your health while also measuring minerals that affect the taste, appearance, and performance of your home’s water.