What is recycled water?

The small group of concerned residents in Woodacre that want to build a sewer plant in the Valley are happy to tell you the benefits of reclaimed water. The sewer plant that they’ve proposed produces an effluent called disinfected tertiary water. Compared to other sewer plants, this is a relatively clean effluent. It’s filtered and treated with UV light. It’s not clean enough to drink but the state of California has decided that it’s clean enough to use for irrigation on the San Geronimo Valley Golf Course. The standards that California has set for the use of reclaimed water is called Title 22. Title 22, along with the Questa Engineering’s Wastewater Recycling Study do reveal some important facts that you need to know. Whether you’re a golfer, a parent or a concerned citizen, you should be aware of what is being produced and sprayed in your community.

  • California mandates that drinking water fountains need to be covered so that they are not sprayed with disinfected tertiary water.
  • Outdoor eating areas or food preparation areas can not come into contact with disinfected tertiary water.
  • Disinfected tertiary water can not be sprayed when wind speeds exceed 30 miles and hour.
  • Disinfected tertiary water can’t be sprayed within 25 feet of a flowing stream.
  • Disinfected tertiary water can’t be sprayed within 50 feet of an ephemeral stream.
  • Disinfected tertiary water can’t be sprayed within 200 feet of a reservoir or lake.
  • Disinfected tertiary water can’t be sprayed within 25 feet of a property line
  • Warning signs must be placed in areas where reclaimed water is being used.

You might be wondering why there would be issues about spraying this kind if effluent if it is so clean. Closer inspection reveals that it is not as clean as you might think. The effluent limits for the sewer plant that a small group of concerned citizens in Woodacre want to build will allow a maximum average of 30 milligrams of suspended solids per liter to be pumped into the new storage ponds that will be used to water the golf course. (Why are they building new holding ponds? We describe that in another article on this website.) Suspended solids is a scientific term for particles that are suspended in a liquid.

Let’s do some quick math. The estimated amount of sewage that would flow through the sewer plant each day is 44,000 gallons (wet weather cycle). There are 3.785 liters in a gallon. The estimated number of liters flowing through the system each day would be 166,558 liters. The average milligrams of suspended solids per liter of effluent is 30. Each day’s amount of effluent is 4,996,740 milligrams or 4.996 kilograms. That’s 11 pounds a day or approximately 330 pounds of human waste being pumped into storage ponds each month and sprayed onto the golf course from April through October. These are, of course, averages and actual numbers may vary but it gives you a good idea of why the state of California doesn’t want this reclaimed water sprayed near drinking fountains or streams. Remember, the golf course is crossed by several flowing and ephemeral streams. In fact, the San Geronimo Creek (that’s the one concerned citizens are trying to protect) flows right through the middle of the course. The course also includes several fresh water reservoirs. How can reclaimed water even be sprayed on this golf course given it’s complexity? Good question. That’s addressed on this website in a section titled ‘setbacks.’

One last thing to know about recycled water. Human waste is not the only thing that passes through the filter. Human coliform bacteria will be present, averaging 2.2 MPN (most probable number) per 100 ml although they are allowed to jump to an average of 23 MPN/ml at certain times. Viruses will also be present and are notoriously hard to remove from waste water. And unlike repeated exposure limits, you only need to come into contact with one human coliform bacteria or one dangerous virus to become very ill.