Ever wonder what happens to water after you're done using it? Where does it go? How long does it take to get there? What happens to it?

If you answered no, you are not alone, as most of us take it for granted! You see the water swirl down the drain. But, what happens next?

On average, each person uses about 70 gallons of water at home each day. For all Las Virgenes Municipal Water District customers, this adds up to about 5.4 million gallons down the drain a day. Another 3.8 million gallons of wastewater comes in from neighboring communities served by our joint venture partner, Triunfo Sanitation District. This brings the total to 9.2 million gallons of water a day, 7 days a week, 365 days a year. That's a lot of water! (For comparison, 1 million gallons of water would fill a football field a little over 3 feet deep!)

It takes nearly 300 miles of sewer pipeline to serve customers throughout the 122-square mile region served by Las Virgenes Municipal Water District. In some areas, garage-sized pumping assemblies called lift stations are needed to move the wastewater over hills or out of valleys before reaching the Tapia Water Reclamation Facility. Tapia is nestled in a geographic low spot in Malibu Canyon, which means most of the district's wastewater flows naturally downhill to reach the facility.

Depending on where you live, it takes your wastewater 1 to 4 hours to reach Tapia. Along the way, materials slowly begin to degrade. Materials like grease and oil from food products will not degrade and can build up within the sewer lines. Objects illegally dumped down manholes are prime candidates for capturing grease and starting a blockage -- just one of the problems sewer maintenance crews routinely check for.

Finally, the wastewater, now called influent, arrives at Tapia for treatment. Because most of us use more water in the morning, when we are getting ready for the day, and in the evening, as we clean up for dinner, the influent actually arrives in predictable rhythms, or pulses. How does Tapia control this fluctuating volume? And what happens to your wastewater as it flows through Tapia to be transformed into highly treated, safe, recycled water for irrigation? Let's follow the flow, step by step.

Step 1:

All influent first enters the headworks where a wide range of material is removed. Your coffee grounds, eggshells, the 2x4 illegally stuffed down a manhole, and those missing socks of yours will be captured here.

Step 2:

Next the flow is slowed down as it enters settling tanks, where the suspended solids (a combination of food and human waste) settle out for approximately 2 hours. This is called primary sedimentation. The solids generally drop to the bottom and the oil and grease float to the top. Both are collected and pumped four miles up the road to the Rancho Las Virgenes Composting Facility. Here, the biosolids are transformed into a useful, rich soil amendment.

Step 3:

The remaining flow (now 99.9% water) goes to the aeration tanks, where air is pumped in and the wastewater is mixed with microorganisms. These tiny beneficial bacteria are the "workhorses" of the treatment process, as they digest and neutralize any remaining solids. This process takes approximately 8 hours to complete. At this point, the influent has been at Tapia for 10 hours.

Step 4:

The flow next moves on to the secondary sedimentation tank. Here the microorganisms are allowed to settle out and are recaptured, to be used to treat another batch of influent. This process takes 4 hours, bringing the amount of time spent at Tapia to 14 hours. And remember those morning and early evening pulses of wastewater? It's at this point in the treatment that the extra volume of wastewater is diverted into a holding tank called a balancing pond to be disinfected and filtered in the early morning hours when flows are lower.

Step 5:

The partially treated wastewater is now ready for filtration, the tertiary or third treatment process. This consists of a series of filters, several feet deep. The filtration process, referred to as "polishing", removes any tiny, floating solid particles remaining. This takes as long as 2.5 hours, which brings the time at Tapia to 16.5 hours.

Step 6:

Moving at a snail's pace, the flow will now slow down for up to 4 hours in the chlorine contact channel. Here the water is disinfected. Once this process is completed, approximately 20.5 hours after the flow enters Tapia, it is almost ready for reuse.

Step 7:

The final step before discharge is to remove the chlorine. Given enough time, chlorine will dissipate naturally, but to speed the process this is done chemically.

If destined for irrigation as recycled water, the water leaving Tapia, now called effluent, will still contain a small amount of chlorine (about 1 part per billion), to maintain water quality within the pipelines. There are also nutrients in the recycled water, by-products of the work done by those hungry microbes, which help to fertilize landscapes, a money saving plus for large Homeowners' Associations, our cities and schools.

Tapia is a "tertiary" treatment plant, processing your wastewater in these steps until it passes all state and federal regulations for irrigation and recreation reuse as recycled water.

Tapia has been honored with numerous awards for excellence of its treatment process and operations. Of the 15,000 treatment facilities in the United States that process over 5 million gallons of water daily, less than 3% have effluent filtration, the tertiary step. As one of these facilities currently capable of producing such high quality recycled water, Tapia is fulfilling an important environmental goal of maximizing reuse of limited water resources in our communities.

And that's the story of what happens to your water after it runs down your drains from your home to the district's pipeline!

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