Urban Water Cycle Story
Most of us understand the basics of the water cycle (evaporation, condensation, precipitation, etc.). But in our urban areas a different cycle is also at work – the urban water cycle. Just as water circulates through the natural water cycle, water in our cities flows in an urban water cycle made up of an intricate system of color coded pipes underground.
The story of your water begins underground. In most of Thurston County, drinking water comes from groundwater. Groundwater is stored in aquifers. Aquifers are layers of rock, dirt, and sand that are saturated with water – think of a soaking wet sponge. We’re lucky to have high quality groundwater that requires little or no treatment to drink. Water is pumped out of the ground through wells that are owned by city or private water systems or private homeowners.
Drinking water is called “potable” water, and we use it for more than just drinking. We use this water in the washing machine and dishwasher, the water heater for tap and showers, and to flush your toilet. It is also used for irrigation at parks, fields, and landscapes throughout neighborhoods.
Water that runs down your drains or toilet is called wastewater. Wastewater needs to be treated and cleaned before it is released back into the environment. This protects human and environmental health. Most of the wastewater in our urban areas is collected through the sewer system and sent to one of LOTT’s treatment plants to be cleaned.
Pump stations are needed throughout the system to help move the wastewater uphill. Gravity then moves the wastewater to the next pump station along the pipeline. Pump stations can get clogged with trash such as flushable wipes, that’s why it’s so important not to use the toilet like a trash can.
Once the wastewater arrives at the treatment plant, there are physical and biological processes to treat and clean the wastewater. Most of the treated water, or effluent, is released into Budd Inlet. For more information on LOTT’s wastewater treatment process view this slideshow or visit LOTT’s website.
Some of the treated water is sent to the Reclaimed Water Plant, where it is cleaned even more. This Class A Reclaimed Water is high-quality water that can be used for irrigation and other non-drinking uses.
Some homes have septic systems that treat their wastewater. Septic systems are used to treat wastewater from homes that are not connected to the regional sewer system. Septic systems are made up of a tank and drainfield. Solids settle in the tank where bacteria go to work to break them down. Liquids flow to the drain field and then soak into the ground where microorganisms in the soil help clean the wastewater. Septic tanks need to be pumped every three to five years. Waste from the tanks is brought to LOTT’s wastewater treatment plant to be treated further. Septic systems do a good job of treating wastewater in rural areas, but too many too close together can pollute streams and groundwater.
Reclaimed water is made from wastewater that is highly treated and cleaned so that it can be used for irrigation and other non-drinking purposes. Purple is the color code for reclaimed water. If you see purple pipes or sprinkler heads, you know reclaimed water is in use. LOTT uses different technologies to make reclaimed water – sand filtration and membrane filtration. Both filter the water and disinfect it to create high-quality water, safe for reuse.
Reclaimed water can be used to replenish groundwater. Reclaimed water moves through purple pipes to LOTT’s Hawks Prairie Ponds and Recharge Basins. The water flows through wetland ponds that make great habitat for wildlife. The water then flows into shallow gravel basins where it soaks into the ground and eventually mixes with groundwater. As the water moves through the soil, helpful microorganisms clean the water even more. After years of flowing slowly underground, the water eventually reaches Woodland Creek and Puget Sound.
Stormwater is water from rain or melting snow that “runs off” across the land instead of seeping into the ground. It picks up pollutants and can be very dirty. Pet waste, fertilizers, and oil from cars are some examples of stormwater pollution. Storm drains usually carry stormwater to special treatment ponds, but sometimes they release the water to streams or Puget Sound. Some of the stormwater from older parts of our communities, like downtown Olympia, is treated at the wastewater plant. Our communities are finding new and better ways to manage stormwater. For instance, rain gardens can mimic nature and use special soil and plants to clean the stormwater before it soaks into the ground.