For San Francisco Bay, winter can bring a surge of pollution from sewage. The primary cause is heavy rains that fill storm drains and infiltrate leaky sewer pipes, causing spills and overflows of raw sewage.
When sewer pipes are clogged by fat, oil and grease from local households, this causes backups of sewage into homes, streets and the Bay. During a drought, heavy storms happen infrequently, but when they do, sewer pipes may have become even more clogged than usual.
Frying any food—and cooking foods like meats, gravy and rich desserts—creates fats, oil and grease which get washed down the drain during cleanup of pots, pans and fryers. The fats and greasy scraps harden and clump together, especially in cold weather. Fats stick to the inside of sewer pipes, and build up over time, causing clogs in home or street sewer lines.
Sewage then backs up in homes, yards and even neighborhood streets. In most Bay Area cities, sewage that enters storm drains flows directly into local creeks and the Bay.
Sewage pollution causes problems that range from skin infections in swimmers to disease in sea lions to algae blooms that choke off the oxygen supply of fish and aquatic plants.
We can all keep our kitchens from polluting the Bay—and avoid sewage backups in our homes and neighborhoods.
Here are the foods not to wash down the drain: cooking oil, meat fat, lard, shortening, butter, dairy products, margarine, fatty food scraps, sauces, gravy and salad dressing.
And here are tips for Bay-friendly fat cleanup:
- Pour fats and greasy sauces into an empty waxed milk carton, store in the freezer until pick up day, then put the whole carton in the kitchen scrap recycling bin. You can also pour cooled fats and oils into a can with a lid, or mix then with an absorbent material such as cat litter, and dispose of it in the garbage.
- Wipe down greasy pots, pans and dishes with a paper towel before washing them. Dispose of the paper towel in your kitchen scrap recycling or in the garbage.
- Don’t use hot water or the garbage disposal to wash fats down the drain. Water cools through the pipes, causing fats to harden into clogs further along in the sewer system.
- Drop off large amounts of cooking oil - like used oil from a fryer - at Bay Area recycling locations.
Photo by Ingrid Taylar (Flickr/CC)