Silica in Drinking Water
Silica in Drinking Water: What It Is and How to Test for It
Silica is a naturally occurring mineral commonly found in drinking water, especially in groundwater supplies and private wells. Silica levels can depend heavily on local geology and vary between homes and water sources.
While silica is not a federally regulated contaminant, high levels can create persistent issues throughout the home — from cloudy glassware to stubborn scale buildup and plumbing damage. Higher silica levels are more common in areas with mineral-rich geology, such as Colorado, California and North Carolina, including regions with sandstone, granite or volcanic formations that naturally release dissolved silica into water.
What Is Silica?
Silica is a hard, glassy mineral and one of the most abundant elements found in the Earth’s crust. Just like calcium, magnesium and other major minerals, silica is found in groundwater supplies at varying concentrations, depending on the surrounding rock.
How Does Silica Get Into Well Water?
As water passes through the Earth, it dissolves silica from rocks and minerals. Because of this, most — if not all — water supplies contain some amount of dissolved silica. It’s also found in certain foods like oats, rice, strawberries and more.
Deeper wells may show higher concentrations of silica when the water has more contact with underground rock formations. Silica levels may shift over time, based on seasonal rainfall, drought and other groundwater changes — making routine water testing important for your home.
Silica is also common in municipal water, especially when the source water comes from mineral-rich surface water or groundwater.
Signs of Silica in Your Home
Silica in water leaves its mark in several ways in your home:
- Dishes and fixtures: Persistent white spots or buildup, as well as etching and scratching.
- Plumbing systems and water-using appliances: Silica builds up in pipes and reduces heating and cooling efficiency and effectiveness, as well as restricting water flow.
- Health and beauty: Can leave hair dry and brittle after washing, cause breakage and poor absorption of hair color.
Is Silica in Drinking Water Harmful?
While silica is not considered harmful to human health in drinking water, high concentrations can impact taste and clarity. Silica is not currently regulated by the EPA under either the National Primary or Secondary Drinking Water Regulations.
Most often, high silica in water causes issues in the home rather than for human health, such as etching on fixtures and glassware, cloudy residue and scale buildup in plumbing.
Silica can also interfere with reverse osmosis membranes, requiring specialized pre-treatment, closer monitoring and cleaning to help mitigate fouling and scaling.
Reactive vs. Colloidal Silica
There are two different forms of silica that end up in water: reactive silica and colloidal silica. Reactive silica is a very weak acid that dissolves in water, while colloidal silica has a glass-like structure that can damage surfaces, glassware and fixtures.
While both forms of silica are harmless when ingested, they can leave behind cloudy or milky spots on surfaces and fixtures, as well as white, chalky build-ups of minerals called scale.
| Reactive Silica | Colloidal Silica | |
|---|---|---|
| Common Signs/Issues | Can cause scale buildup | Can cause fouling in equipment, such as RO membranes |
| Removal | Ion exchange resin; reverse osmosis | Requires more advanced treatment, such as ultrafiltration or RO |
| Form | Dissolved in water as ions | Tiny, undissolved particles suspended in the water |
How to Test for Silica in Water
The most reliable way to measure silica concentration in water is through professional water testing services. At Kinetico, our free water analysis covers silica for both well and municipal water, as well as many other dissolved solids, sediment, hardness minerals, iron and more.
DIY water tests tend to be less accurate and usually require specialized colorimetric test kits, or sending a sample into a lab. These kits can help screen for reactive silica, but not total and colloidal silica, resulting in a less precise diagnosis of your home’s water problems and how to treat them.
Get your water tested for silica if you:
- Notice etching, cloudy stains or spotting on dishes and glassware, including shower doors
- Are experiencing reduced water pressure
- Have scale buildup in appliances or around fixtures
- Rely on private well water
The Best Treatment Options for Silica Removal
There are multiple treatment options for removing silica from water, on both residential and commercial levels, based on identifying what type(s) are found in your water. After determining this through a free water test, here are the solution options.
Reverse Osmosis
Reverse osmosis water purification systems have the advantage of removing both molecules and ions from water, effectively dealing with both reactive and colloidal silica in the process. At over 99% removal rates for all contaminants, RO is one the best methods of treating for silica while also providing you with the best water possible.
This solution is ideal for drinking water quality. Some pre-treatment is still required for colloidal silica. RO systems also need annual maintenance and eventual membrane replacement, but Kinetico can advise on and help with this.
Ion Exchange
Ion exchange water softener systems significantly reduce dissolved ions from water, making them perfect to deal with the negative charge of reactive silica. With a negative charge, anion resin is the required media. Occasionally, these systems will need additional crystalline salt to continue working, which is something Kinetico can help with/deliver to you.
Additionally, due to the constraints of testing, it is difficult to determine the silica type and whether or not ion exchange will be effective for the type of silica present in your water.
Ultrafiltration
Ultrafiltration systems have extremely fine membranes, giving them the ability to filter out solid matter on a microscopic level. Because colloidal silica is suspended in water, ultrafiltration is great for its removal. However, these systems cannot effectively remove reactive silica.
A challenge of this silica removal option is being able to determine the type of silica in your water as there are not feasible testing options to determine silica type and particle size. For this reason, we recommend treatment options that either sequester the silica preventing etching or removing silica through a process of reverse osmosis.
Sequestration
Silica sequestration systems do not use filtration, ion exchange or reverse osmosis to target silica but sequester the silica by using a sequestering agent to prevent etching and scale. These systems will require replenishment of the sequestering media over time which will vary depending on water use. Due to the fact that these systems introduce a sequestering agent to the water, they are not ideal systems for drinking water where high levels of purity are recommended or necessary.
Treat Silica in Your Water With Kinetico
If you think silica could be causing damage in your home, get started with free professional water testing from Kinetico. Our local water experts will walk you through the best water treatment options for your budget, providing custom solutions specifically for your home.
