Page Index
Wastewater Department
Maintenance Activities
Frequently asked questions (FAQ’s)
Do’s and Don'ts
Wastewater Request Form


Easy Guide to Easements (240k)
If you wish to have a copy mailed to you, contact (510) 537-0757.

Easement Considerations:

The location will be determined from recorded maps or a grant of easement document.

Keep the location of the easement clear of debris and material, especially around manhole access points.

The property owner may be faced with all costs of removal and any associated damages resulting from unauthorized structures or improvements on land subject to an easement.

We would appreciate if you could provide us with your name and contact number so we can make special arrangements with you regarding the care for your dog before entering your property

Wastewater Department

The purpose of the Wastewater Program is to collect and convey all wastewater produced within the Castro Valley Sanitary District (CVSan) to the Oro Loma/Castro Valley Wastewater Treatment Plant in San Lorenzo. This is accomplished through establishing specifications for the construction of sewer lines, inspecting lines for compliance with those specifications, conducting preventive maintenance of the system, repairing and replacing defective elements of the system, and managing flow rates to stay within the capacity of the collection and treatment systems. The collection system maintains approximately 160 miles of wastewater sewer mains and nine (9) sewage pump stations.

The Wastewater Department is divided in two divisions; Collection System Maintenance and Engineering.

Maintenance Activities

Preventative Maintenance – This is maintenance that the collections system crew does on a monthly basis in areas know as “hot spots.” In order to minimize and prevent sewer backups, this division is responsible for a preventative maintenance program that includes periodic television inspection and cleaning of the sanitary sewer system.

Basin Maintenance – Basin Maintenance is maintenance that is performed in one specific area of the District. Each public sewer line in this area is first cleaned and then televised to see the structural condition of the public sewer pipe. This maintenance is done in compliance with the Sanitary Sewer Management Plan (SSMP).

Corrective Maintenance – This maintenance is performed to repair defects found through out the sewer system that have the potential to cause a stoppage or failure. The District hires a contractor to repair or rehabilitate these sewer pipes.

Service Calls – The District field personnel respond to service calls related to the sanitary sewer system. This includes but it not limited to investigation of sewer back-ups, manhole investigation, etc.

Sanitary Sewer Overflow Emergency Response – The District responds to all CVSan sewer overflows that occur in the public sewer system. The District is dedicated to protecting public health and the environment.

High Velocity Cleaner– This self-contained vehicle is a heavy-duty high velocity cleaner that uses high pressure water to clean and maintain sewer facilities and occasionally assist with breaking stoppages. The District’s unit holds up to 600 gallons of water and is capable of cleaning sewer lines up to 8” in diameter.

Combination Unit – This self-contained vehicle is a heavy-duty combination vacuum/high velocity cleaner that uses high pressure water to clean and maintain sewer facilities and occasionally assist with breaking stoppages. This unit differs from a high velocity cleaner because it has the ability to vacuum debris from manhole channels. The Districts combination unit holds 400 gallons of water and has a 3 cubic yard debris tank that can hold an additional 1,000 gallons of water when not being used for debris collection. This unit is capable of cleaning sewer lines up to 60" in diameter.

Machine Rodder – This self-contained vehicle is a heavy-duty unit that is used to maintain sewer lines that are know to have “roots” and occasionally assist with breaking stoppages within the sewer facilities by mechanically inserting a metal rod with a cleaning tool attached at the end, into the sewer lines to clear obstructions. Our unit is capable of cleaning sewer lines up to 15” in diameter and has 1000’ of rod..

Closed Circuit Television (CCTV) Inspection Unit – This unit allows the collection system crew to visually inspect underground facilities thru the use of an underground camera that transmits video through a fiber optic cable to the above ground vehicle. Our unit is capable of inspecting sanitary sewer lines up to 24” in diameter and a maximum length of 1000’ at one time.

Request for service – See attached form.

Frequently asked questions (FAQ’s)

Q. What is a collection system?
A. A collection system is a network of pipes, manholes, clean-outs, lift stations and other structures used to collect all wastewater and transport it to a treatment plant or disposal system. CVSan is a collection system only. Treatment and disposal take place at the Castro Valley/Oro Loma Wastewater Treatment Facility in San Lorenzo.

Q. What is a Sewer Service Charge?
A. The purpose of the sewer service charge is to raise revenue for the cost and maintenance and operation and for renewal and replacement of the facilities necessary to collect, treat and dispose of wastewater generated from your home or business to ultimate deep-water discharge into San Francisco Bay.

Q. How do I pay my Sewer Service Charge?
A. The District uses the Alameda County Tax Rolls as the primary method of collection of the Sanitary Sewer Service Charge on an annual basis. This line item shows up on the property owner’s property tax bill under the Special Assessments section.

Q. How does my rate compare to other sewer service charge rates in the area?
A. The District has one of the lowest rates in Alameda County and lower than the average annual charge in the State of California.

Q. When there's a sewer backup what should I do?
A. When a backup occurs, contact CVSan’s Main Office at 510-537-0757 during business hours (7:00 a.m.-4:00 p.m. Mon-Fri) or (510) 506-5821 after hours.

Q. What will the District do when a backup occurs?
A. CVSan will assess the backup to determine if the blockage is in the public sewer line or the property owner’s private sewer lateral. CVSan will clear blockages that occur in the public sewer line only. Property owners are responsible for blockages that occur in their private sewer lateral, located within two (2) feet of the foundation wall of the building and extending to and including the connection to the public sewer line.

If it is determined that the public sewer line is blocked, only CVSan has the authority to clear the system. If the public sewer line is clear, the District’s representative may advise the property owner to contact a plumbing contractor to perform maintenance to their private sewer lateral.

Q. What is the purpose of manhole lids?
A. The manholes circular metal lid usually located in the middle (sometimes to the side) of the roadway are for access to the sanitary sewer pipe. Only authorized District personnel can remove the manhole. Unauthorized entry into manholes is extremely dangerous and strictly prohibited.

Q. If I notice missing, damaged or noisy manhole lids (loose fitting) what do I do?
A. Please report it to the District immediately.

Q. What do you mean by sanitary sewer system?
A. Sanitary sewer systems are the collection of pipes, pumps and lift stations, manholes, service lines, and other infrastructure throughout the District designed to handle and safely transport used water, body wastes, and toilet paper as sewage to a treatment plant.

Q. What causes a sanitary sewer to backup?
A. Most sewer backups happen because the line is plugged with an obstruction. However, backups can be caused by several factors including the condition of the sanitary sewer system itself, natural phenomena such as earth movement, heavy rainfall, and the incorrect usage of the system by the public.

Some common backup causes are:
Solids / debris – Typical solids that buildup in the pipe and cause backups are dirt, hair, bones, tampons, paper towels, kitty litter, diapers, broken dishware, garbage, concrete, and debris.
Fat/Oil/Grease - When fat, oil or grease is discharged into a sewer system they will solidify and, after a while, can build up and plug drain lines in your building or complex. They can also plug the sewer lines owned by the District, thus increasing the maintenance cost to the District. Plugged sewers can also cause flooding of nearby private homes and businesses.
Tree Root infiltration – Tree roots can cause backups. Roots can infiltrate the pipe system and block the wastewater flow.
Water inflow/infiltration – Rainwater entering the public sewer line can cause system problems and overflows. If the sanitary sewers only transported wastewater, backups would only occur when obstructions were present in sewer pipes. However, during certain wet weather conditions, sanitary sewers can become overloaded with groundwater or storm water runoff so they become surcharged or overloaded. This results in backups into lower levels and basements, or slow running services.
Structural defects in pipes and manholes – Significant sags, bellies in the line, cracks, holes, protruding laterals, misaligned pipe, offset and open joints and collapsing pipe material are all possible causes of backups.

Q. What kinds of problems do fat, oil and grease cause?
A. Sewer capacity constraints are frequently caused by improper materials, including fats, oils, and greases being introduced into the sewer system by District residents and businesses.

Q. How big is the grease problem?
A. From 50–70 percent of all sanitary sewer system problems overflows are caused by accumulations of fats, oils and greases discharged to it from the preparation and serving of food.

Q. Where does the fat, oil and grease come from?
A. Many sources. In the food industry, "grease" often refers to fats and oils derived from animal and vegetable sources. These include meats, nuts, cereals, beans and waxes. paraffin’s.

Q. What is an Easement?
An Easement is a legal document that conveys limited property rights from the Grantor (Property Owner) to the Grantee (Castro Valley Sanitary District). This document is usually recorded in the office of the Alameda County Recorder.

A sanitary sewer easement creates a non-exclusive, perpetual right to use a portion of your property for sanitary sewer purposes. This provides the District with access rights to repair, replace, inspect, enlarge, change, maintain, test and/or remove the sanitary sewer located within the easement.

Q. Who owns and maintains the Easement?

The Property Owner continues to own the land and has only given up defined rights on the portion of land used for the easement. Maintenance of the property within the easement is the responsibility of the Property Owner.

Q. What is the size and location of the Easement?

The easement is typically ten feet wide (five feet on either side of the sanitary sewer), however, the size may vary. The location will be determined from recorded maps or a grant of easement document. If you are unfamiliar with the size and location of your easement please contact your title company or the District at (510) 537-0757. 

Q. Who can enter my property?

The District, if it has an easement, may go onto the easement at any time. The District may, on occasion, have a Contractor present to perform specific tasks relating to the District's operations. We will make an effort to notify you prior to entry, however, in the case of an emergency we may need to enter without prior notification. Please request, at any time, to see District personnel photo identification cards, or contact the District at (510) 537-0757.

Q. Can I make improvements within the Easement?

Easement are typically granted to the District with the understanding that the property owner may make improvements to the surface such as fences, asphalt paving, trees, irrigation and lighting systems or similar improvements. As part of the agreement, the District is permitted to remove any of these improvements for the purpose of maintaining and/or replacing the sanitary sewer. Please note that the District is not liable for any damage to your improvements.

Q. What does this mean to me?

  • Do not place planters or any other 
objects on manhole covers.
  • Fences and gates are not to be 
constructed over manhole covers.
  • No permanent structures are to be 
erected within the easement location.
  • Keep the location of the easement 
clear of debris and material, especially 
around manhole access points.
  • Planting of trees within the easement is 
not permitted without prior approval 
from the District.

• For more information on keeping the area clear within the easement, please contact the District at (510) 537-0757.

Q. What is an encroachment on an easement?
A. An encroachment is a physical intrusion in an area of the easement contrary to the agreement. The District may require that any unauthorized encroachments be removed at the property owner's expense. All encroachments on easements require written approval of the District by way of an Encroachment Agreement. 

Q. Are there penalties for locating structures or improvements on an easement?
The property owner may be faced with all costs of removal and any associated damages resulting from unauthorized structures or improvements on land subject to an easement.

Q. Do you have a dog?

The District makes every effort to try to minimize impacts on you, however, if you own a dog this makes our work a little more challenging!

We would appreciate if you could provide us with your name and contact number so we can make special arrangements with you regarding the care for your dog before entering your property. Please contact us at (510) 537-0757.

Note: We would appreciate if you could provide us with your name and contact number so we can make special arrangements with you regarding the care for your dog before entering your property.

Do’s and Don'ts

DO’s - Following the suggestions listed below may save residents money and avoid significant inconvenience, as well as cost to the community for clearing and repairing blockages. In some instances, depending on where the blockage is located, the property owner or resident may have to bear the cost of clearing the line. Also, when an overflow occurs, do to a blockage, there may be environmental impacts.


Do let liquid fat, oil or grease cool and dispose of it in your organics bin/cart. If your pots and pans are just oily or greasy, wipe them clean with a paper towel and put the soiled paper towel in the organics bin/cart.

Do place food scraps and excess grease in the organics bin/cart, or start a compost pile; promote use of scraping of dishware prior to washing.
Place a wastebasket in the bathroom to dispose of solids wastes. Disposable diapers, condoms, and personal hygiene products do not belong in the sewer system.

Do use a strainer over the plughole in your sink, tub and shower. Then, empty the collected material into the garbage.

Do use a composter. If you haven't got a compost heap, start one with lawn clippings, garden rubbish and food scraps and use the compost to fertilize your garden.

Do use the manufacturer's recommended amount of detergent for washing up in the kitchen or laundry. The average household uses three times more detergent than manufacturers recommended for washing dishes and clothes. When these detergents enter the sewerage system, they hold large amounts of oil, grease and fats in suspension making cleaning and treating the wastewater difficult and more costly. In addition to saving money on buying detergents, by cutting down on the amount of detergent used, there'll also be less phosphate in the environment to cause the growth of algae in water.

Do take care not to drop dentures and wallets into the toilet.


Do not pour fats, oils and grease from cooking down the sink drain.
Why? If your pots and pans are just oily or greasy, don't rinse them; wipe them out with a paper towel.

Do not pour sour milk down the sink.
Why? One liter of full cream milk has enough fat in it to cover the surface of an Olympic-sized swimming pool.

Do not use the toilet as a wastebasket / garbage can.

Do not use the sewer as a means to dispose of food scraps.

Do not wash food scraps, tealeaves, coffee grounds and eggshells down the sink.

Do not flush razor blades, condoms, pharmaceutical products, cigarette butts, nail polish remover, toilet deodorant dispensers or other non-biodegradable products down the toilet. Also, toys can find their way into the system and cause problems.

Do not place jewelry and valuables on the edge of the basin or the sink
Once flushed down the toilet, valuable and valued items are very difficult to recover.

Do not flush diapers, sanitary napkins, tampons, convenience pads, surgical bandages, syringes, and cotton tipped stems or pantyhose down the toilet.Do not dispose of plastics and plastic film from personal hygiene items, including disposable diapers.

Do not pour paint, engine oil, pesticides or chemicals down the sink, and don't try to burn them. Some hazardous materials can corrode the sewer, while others complicate the treatment process. In fact, dumping them in the sewer is illegal and you could be heavily fined. This isn't only because of the threat of these hazards getting into the environment; but also because these chemicals pose a health threat to maintenance crews working in the sewers. Similarly, by throwing hazardous materials in the garbage, you are creating a risk for garbage collectors. Instead, contact the Alameda County Household Hazardous Waste Department (800) 606-6606 for advice on where to take them for safe disposal. Also, don't ever try to burn these chemicals on your barbecue, fireplace or in the incinerator - they could produce toxic fumes that could seriously damage your health.

Do not flush a commercial grease interceptor with hot water to clear or clean the interceptor in lieu of cleaning and pumping out the interceptor

OLSD Treatment Process