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Mission Statement
Understanding Sewers
Pipes Underground
Sewer Backups
Who's Responsible for Sewer Backups?
How to avoid sewer problems

To prolong the life of the collection system infrastructure and transport waste to point of treatment without disruption or overflows, while meeting the needs of the citizens in our service area and all Federal, State and Local regulations.
Have your ever stopped to think what happens after you flush? All the "used" water from your toilets, tubs and sinks-we call it wastewater-flows into a hidden world of underground sewer pipes. You'll find that world well worth exploring, because understanding how your sewer system works, and who to call if you have a sewer stoppage, can save you time and money.

The people who keep the sewers running smoothly throughout the service area-all of us at the North San Mateo County Sanitation District (NSMCSD)-will also let you in on a secret: the two most common causes of sewer backups, and how you can avoid them.
  Sewers Carry the Load
Hidden beneath your feet, an intricate web of thousands of miles of sanitary sewers collects wastewater from homes, businesses and industries. Although virtually invisible, this wastewater collection system plays a vital role in protecting public health. In the NSMCSD alone we maintain over 178 miles of sewer pipe!

  Sewer Maintenance and Operation

The Collection System Maintenance Section involves preventive and corrective maintenance of the sanitary wastewater mains in the City of Daly City, Unincorporated Broadmoor, and contractual services to the Town of Colma , the Westborough Water District and the San Francisco Jail. The Section provides preventive maintenance to eight sewage lift stations, four in Daly City, one in Colma, and three in the Westborough Water District.

  Pipes Come in All Sizes
The smallest sewer pipes, six inches or less in diameter, are known as "collectors." Wastewater from homes, businesses, schools-in short, any building-enters the system via these service lines.
After leaving the collectors, wastewater flows into a system of "trunk lines"-larger pipes with a diameter greater than 12 inches and a capacity ranging from one to ten million gallons per day (mgd).
Finally, these trunk lines connect to a central system of giant "interceptors," that carry wastewater directly to our Wastewater Treatment Plant located on the corner of John Daly Blvd and Lake Merced Blvd. The interceptors can be as large as 3.5 feet in diameter. NSMCSD owns and operates the treatment plant and the interceptor system that serves Daly City, Broodmoor, Colma, Westborough and the San Francisco Jail.
  Call Us First
If you have a sewer backup, you can save time and money by calling us first, before you call a plumber, at (650) 991-8200. Maintenance crews are available to respond to your sewer service calls seven days a week, 24 hours a day, 365 days a year. We'll determine whether the sewer problem is NSMCSD's responsibility, at which time we'll fix it at no charge to you or if the stoppage is on your property, at which time we'll advise you to call a plumber.

Our Service Call Response
Our crews make every effort to respond to your service call within one hour. Our average response time is within thirty minutes.

Accessing Sewers for Maintenance
If you have a sewer maintenance hole (sometimes called a "manhole") on your property, our crews may need access to it for routine maintenance or emergency repair. Some homes have sewer "cleanouts"-smaller openings into which equipment may be lowered to inspect and evaluate the condition of the sewer service line.
Sewer Mains: NSMCSD is responsible for backups in sewer mains.

Side Sewers: Property owners are responsible for maintaining side sewers. Side sewer means the sewer line beginning at the foundation wall of any building and terminating at the main sewer and includes the building sewer and lateral sewer together. Where the side sewer provides service to single-family residential units with common walls, condominiums, stock cooperatives, community apartments or other similar improvements, the obligation to maintain the side sewer shall be the homeowners' association or other entity responsible for the maintenance of the property and facilities owned in common. (Ordinance 56 § 4.8, 1982)
The two most common causes of sewer backups are:

Putting items down your sink that should be put into your garbage.
Invasive tree roots.

That's the bad news. The good news is that both are often preventable. Here's what you can do to help avoid problems in your sewer system:
Don't put grease, oil or egg shells down your sink. When grease and egg shells combine they create a mixture similar to concrete; oil sticks to the pipe at the waterline. Both of these conditions can clog the sewer line. Instead, keep a small, empty container handy to contain these items. When the container is full, put it outside with the garbage.
Avoid trees with shallow, spreading root systems. Tree roots tend to grow towards sources of water-like sewer pipes. Two of the most troublesome species of trees are the fruitless mulberry and the Modesto ash. If you're upgrading your home's landscaping, you can save yourself headaches and money by choosing trees with deep root systems.
After you select a tree, follow proper planting procedures. Be sure to dig a hole deep enough to cut below heavy clay deposits. If your hole is too shallow, the tree's roots won't be able to penetrate the clay, and they'll spread out horizontally. The tree won't be healthy . . . and neither will your sewer system.

Speaking of things you shouldn't put down your sink . . .

Many consumer products are considered household hazardous waste. Never pour items like these into your sink or toilet:

Motor Oil
Antifreeze Solvents
Wood preservatives
Paint Lighter fluid
Many other common consumer products

For more information about household hazardous waste and a schedule of collection days and locations, call the San Mateo County Household Hazardous Waste Program at 650-363-4718.