Greener Davis has complied some of the most frequently asked questions they get regarding what should and shouldn’t go down the drain. If you have a question that you feel would be of interest to the community, please email it to, and you may see it featured in an upcoming column, Greener Davis e-blast, on the website or in a social media post. Find out more at

Check out this infosheet for more details!

Q. Where does the water go when it goes down the sink, shower or toilet?

A. It goes through a large system of underground pipes (using gravity) and pump stations (when the gravity needs help) to get to the city’s wastewater treatment plant about 5 miles north of the city center.

Q. I have extra medications that I don’t need anymore. Is it ok to flush them down the toilet?

A. No! Wastewater treatment methods, even the recently upgraded treatment that occurs at the treatment plant, do not remove medications from the water. To prevent environmental contamination, prescription and over-the-counter medication should never be flushed down a toilet (or thrown in the trash). Instead, take the medications to one of the drop-off locations listed below for safe disposal:

  • Yolo County Central Landfill Household Hazardous Waste Drop-Off Facility, 44090 County Road 28H, 7:30 a.m. to 3:30 p.m. every Friday and Saturday ;
  • UC Davis Clinic Pharmacy, 2660 W Covell Blvd., 9 a.m. to 5:30 p.m. Monday through Friday (closed 12:45 p.m. to 1:30 p.m.);
  • UCD Police Department, 625 Kleiber Hall Drive, 8 a.m. to 5 p.m. Monday through Friday;
  • City of Davis Police Department, 2600 Fifth St., 10 a.m. to 5:30 p.m. Monday through Thursday and every other Friday; and
  • Kaiser Permanente Davis MOB Pharmacy, 1955 Cowell Blvd., 9 a.m. to 6 p.m. Monday through Friday.

Q. If I run hot water, can I pour fats, oils and grease down the drain?

A. No, that’s not a good idea. What might seem like liquid when you’re done cooking can solidify when poured down the drain. Pouring hot water or soap down the drain will not help. In fact, it can only break up the grease temporarily. Fats, oils and grease build up on the walls of sewer pipes and block the plumbing, which can lead to sewer backups in homes and onto streets. Clogged sewer lines can lead to expensive plumbing maintenance for you and the city.

Instead, wait until the fats, oils and grease are cool, then soak up small amounts with paper towels and place the towels in the organics bin. Save larger amounts to recycle for free at the Household Hazardous Waste facility at the landfill.

Q. Is it OK to put food scraps down the garbage disposal?

A. It’s okay, but it’s not the best idea. While your garbage disposal may be able to handle food scraps, sewer pipes are meant to convey liquids with only a small amount of solids. With people continuing to conserve water at home (way to go Davis!), there is often less water going down the drains. Lower volumes of water and increased solids from garbage disposals can lead to clogged sewer pipes, both in your home, and in the city’s underground sewer system. Besides — there’s a better option available! Instead of sending your food scraps to the Wastewater Treatment Plant, you can place them all in your brown-lidded organics cart so it can be turned into a beneficial nutrient-rich compost.

Q. Can I flush those “flushable” wipes down the toilet?

A. No, please don’t. Flushable wipes are not flushable (even if the packaging states they are!). Wipes do not break down like toilet paper does in water; they typically maintain their structure, and when flushed down the toilet, they can cause major backups and clogs within the sewer lines. The toilet is not a trash can, so place wipes where they belong — in a real trash can.

— Sandra Macomb is an environmental program specialist for the city of Davis. Reach her at This column is published monthly.

Published online on June 9, 2021 | Printed in the June 9, 2021 edition on page A3