Delta Fountains' Blog

  • September 17, 2014

All about Turbidity

turbidity - turbid water in glass


Just as water shortages are a big concern in some areas of the country, water quality is a major concern for the world. As fountain designers and manufacturers, an important aspect of our industry is to control the water quality in our fountains, both for public health and aesthetic reasons. In more recent years though, we’ve been pleasantly surprised that the rest of the world has caught on to our concern. The health kick has spread, and we find more and more that clients are coming to us looking for insights into water quality. In order to start to explain water quality to anyone though, it’s important to first start at the heart of the process – filtration and turbidity.

Filtration for fountains

In order to achieve optimal water quality, a good filtration system and strategy must be in effect. Since people could be directly coming into contact with the water in public fountains, it’s important to make sure that the water is safe enough to ingest. At Delta Fountains, we focus on utilizing one of three types of filtration media in our fountain systems: cartridge, sand, and Diatomaceous Earth (DE). Each of these types of filtration systems has unique ways to filter through the microscopic particles and organisms that could be in your water. This helps control the turbidity and ingestability of the water before it gets to the fountain. 

What’s turbidity?

According to the United States Environmental Protection Agency (EPA), “Turbidity is a measure of the cloudiness of water.” Public fountains, interactive fountains, and splash pads are some of the many water features subject to a strict standards enforcement and documentation of water turbidity. This strict monitoring is due, in part, to the fact that some of the most common microscopic impurities that cause the “cloudiness” found in water sources are clay, silt, plankton and other microscopic organisms. Forget the fact that most people turn their noses up to possibly ingesting things like clay; ingesting or even coming into high levels of these same impurities can also cause diseases and other recreational water illnesses (RWIs). According to the Center for Disease Control (CDC), “The most commonly reported RWI is diarrhea. Diarrheal illnesses are caused by germs such as Crypto (short for Cryptospordium), Giardia, Shigella, norovirus and E. coli.”  


What other negative factors can poor filtration and turbidity have on a fountain?

There are several reasons why a high turbidity level is bad for your fountain. If the gross factor doesn’t get you motivated enough, consider the chlorine levels and Department of Health standards as driving points behind your filtration fever. Just like the swimming pools, chlorine is used in fountains to disinfect the water. However, if your water houses too many particulates, microorganisms may begin to grow on the particles and could be harder to kill. The particles themselves may also chemically react with the chlorine, making it difficult to maintain a chlorine residual in the system. This lack of control could allow bacteria to grow.

Similarly, if your fountain water is too turbid, the particles in the water will cause light that passes through it to be scattered and absorbed by the suspended molecules and particles rather than being transmitted in a straight line through the water. This means that even using the recommenced backup UV Sanitizers that can kill microorganisms and bacteria, and that comply with Department of Health standards, would be essentially useless. If the light can’t pass straight through the water, it can’t render any remaining particles or organisms dead or microbiologically unable to reproduce.


No “Cloudy,” no problem?

Much to the dismay of many fountain owners, turbidity cannot be measured by “cloudiness” alone. There are times when your water can be turbid, but not cloudy. Imagine filling a glass with water from an outside hose. Your water may look clear, but when held up to the light you can often find little particles floating throughout your water. Even though it looks clean, some particles still get through the city’s filtration systems. Knowing this, many state Departments of Health have instituted strict daily and monthly monitoring schedules. In New York, the turbidity of water in a public fountain cannot reach more than 3 Nephelometric Turbidity Units (NTUs) before it is declared unsafe. This is a low number, when considering NTUs can reach into the thousands.

turbidity tweetable via delta fountains "Turbidity cannot be measured by "cloudiness" alone."


How do we control turbidity?

Turbidity can be monitored and controlled with a good filtration system. Out of the three most common types of filtration medias, we’ve found Diatomaceous Earth (D.E.) systems, although not often recommended, to be the most effective when controlling turbidity. D.E. is an organic, chalky substance that can trap particulates as small as five microns, or 1/10 the width of a human hair. This leaves your fountain able to filter contaminates like body oils, suntan lotions, pollen, dust and even some bacteria.

Although the FDA has deemed D.E. as GRAS, Generally Recognized as Safe, there are some health hazards to those who are managing these filters and ingesting the powdery form on a regular basis. The pressurized and heated form of D.E. is highly difficult to work with and can produce crystalline silica. Crystalline silica can cause lung disease, respiratory and eye irritation, or other complications. Due to these health hazards, we only recommend this D.E. filtration media when there is a high chance of continual turbidity in your fountain.

On the opposite end of the spectra, Sand filters are the least recommended filtration media for commercial fountains. Sand is only able to filter particles as small as about 22 to 25 microns. While this is a good choice for fountain with a low chance of turbidity, most interactive fountains and splash pads need a more powerful filter to create safe water levels for human contact.

If there is a moderate to high chance of turbidity, and D.E. is not ideal for your needs, cartridge filtration systems are a close second in terms of how small of a particulate they can catch. Cartridge media filters can catch particles as small as 12-15 microns and are relatively easy to maintain. Cartridge media filters are the most common filters used in commercial fountains, and are very effective to meet strict turbidity standards.


If you have questions regarding which filtration media to use in your commercial fountain, call us at 904-886-9030. We would be happy to help walk you through each option in order to determine which filter media is right for your needs.