Water Treatment Process

Renewable water

As Castle Rock continues to grow and change, so has its source of water. In the past, we have received most of our water from wells pulling from an underground aquifer. Today, we are looking, at a variety of renewable surface water sources, including alluvial well water from East Plum Creek and importing water from northern sources. These sources require different considerations for water treatment. Our flagship, the Plum Creek Water Purification Facility (PCWPF), was built in 2013, giving the Town flexibility in choosing and obtaining water sources. 

The PCWPF is open to the public for tours on specific days to teach customers about the advanced technology involved in the water treatment process and gain an appreciation as to why this state-of-the-art facility was recently featured in the Colorado Public Works Journal.

Water treatment is designed to remove a variety of particles or constituents for health and aesthetic purposes. During the steps, constituents such as suspended solids, bacteria, algae, viruses, fungi, and elements like iron and manganese are removed. Water purity
is tested many times throughout the treatment process, and Castle Rock Water consistently meets or exceeds water quality testing parameters. The water purification process is completely automated but monitored continually and adjusted as necessary by operators.

Water purification process

Step 1 - Aeration
Aeration brings air into contact with the raw water in order to removed dissolved gases, as well as oxidizing dissolved metals such as iron and manganese.

Step 2 - Coagulation and flocculation
After aeration, chemicals are added to the water at prescribed dosages and mixed to promote coagulation or clumping of the suspended particles produced through oxidation. During coagulation, the water is gently mixed causing the fine, light particles to clump into larger, denser, particles or floc. 

Step 3 - Sedimentation
The flocculated water then travels into settling basins or clarifiers where gravity allows the particles to settle. The settled particles form a sludge layer on the bottom of the sedimentation basin which is then transported to a sanitary sewer.  

Step 4 – Filtration
After sedimentation, the water passes through several filters, and any particles remaining in the water adhere to the filter media. At PCWPF, the sand and anthracite filter has a special coating to further oxidize the dissolved particulates. For the final filtration, microfiltration, water is pushed through a membrane to remove particles such as bacteria, viruses, and other microorganisms that are less than .1 microns (one-ten thousandth of a millimeter).  

Step 5—Disinfection
Disinfection of drinking water is required to inactivate any microbes that might still be present. Chloramines (chlorine and ammonia) are added to aid in keeping the water clean while it flows through the distribution lines and into your home.
The Plum Creek Water Purification Facility can currently yield about 4 million gallons of potable water per day and is the primary treatment facility for Castle Rock. For high demand periods such as irrigation season, as well as accommodating for maintenance and emergencies, the Town will utilize the three other treatment plants. With Founders, Meadows and Ray Waterman treatment plants online, another 12 million gallons of water can be treated daily.

Another way we ensure safe, reliable and great tasting water is through the rigorous state and national certification for our plant operators. Watch this Professional Operator Association video highlighting Plum Creek Water Purification Facility and our plant operators.

Disinfection with chloramines
Currently, most of Castle Rock’s water comes from nonrenewable wells - some as deep as 2,000 feet below ground. In the past, chlorine alone was used to disinfect the water. Renewable water sources can contain natural organic matter which can interact with chlorine and cause the formation of byproducts. In May 2013, the Town began treating its water with chloramines, which is a combination of chlorine and ammonia. Using chloramines in place of chlorine reduces the likelihood of disinfection byproducts formation, protects your water longer throughout the distribution system and makes your water taste better. 

While this process is relatively new to Castle Rock customers, many municipal and private water providers across the United States and Canada have used this safe, effective disinfectant for more than 90 years. Denver, for example, has been using chloramine to treat its renewable water since 1917. 

Like chlorine, chloramine must be removed from water before it can be used for kidney dialysis or for fish and aquatic life habitats. Chloramines do not dissipate like chlorine and is harmful if it enters the bloodstream directly, but is benign if ingested.  It is recommended to use a dechlorinating agent for chloramine for aquatic life and dialysis machines.  For more specific information, visit the Environmental Protection Agency's Chloramines