Under the current ordinance, properties that are above grade are required to connect to a public sewer system, allowing sewage to flow downhill from the residence to the system by way of gravity. As opposed to septic tanks, which separate waste on the property and return filtered water to the ground, sewer systems transport waste to a treatment facility where contents undergo a number of filtering steps and are delivered to the bay.

The connection requirement left below-grade homes with septic tanks exempt due to the high costs associated with converting and installing a storage tank, a pumping system and necessary pipelines. However, growing concerns about water contamination at a nearby creek are forcing the city to reevaluate homes under exemption.

There are a known 15 properties that will be affected and connected to the Cupertino Sanitary District sewer system should the ordinance be passed. Some of these residents expressed opposition to converting to a sewer line without seeing proof that septic tanks contribute to contaminated creeks.

"Conversion is unnecessary," said resident Rollin Buckman. "The system has been functioning for many decades. My children and neighbor's children played in the creek with no ill effects. There needs to be further study rather than being obdurate and laying blame without proof."

Lack of quantifiable data is why Saratogan Regina Oldham said she is also skeptical that switching to a sewer line would improve the quality of the creek water.

"Contamination can be caused by a number of things," Oldham said. "For example, there are a number of dogs in the neighborhood that may be dropping waste in the creek. Also, it's possible that there may be cracks in the sewer lines where waste can be leaking out."

Although Oldham said she would be more willing to convert if the city provides proof that septic tanks are a threat to the creek, there are other environmental issues to consider.

"We may be solving one problem by changing to a sewer system, but we may also be creating another problem," she said. "Filtered freshwater would be disturbing the bay's equilibrium. If the issue is about septic tanks, the cry becomes 'save the creeks,' and if the issue is about sewer systems, the cry becomes 'save the bay.' "

For other residents such as Bob Binkley, the main concern is the cost of converting to a sewer system. According to estimates, it would cost approximately $63,000 to connect to the sanitary district, install a pumping device, attach 200 feet of piping and dispose of the septic tank.

"The major expense of connecting would have a severe impact on our household finances, and in our case, does not make sense," stated Binkley, whose specialty used to be designing wastewater disposal systems when he worked as a civil engineer. "The proposed ordinance is unfairly blanketing all properties, even those far from the creeks with excellent on-site systems that do not impact creek-water quality."

Cost and doubt in the effectiveness of sewer systems on water quality are some reasons why concerned resident L. Martire said he is against converting, but, as stated in a letter to the city's assistant engineer, Iveta Harvancik, installing a sewer system would not only cause appreciable collateral damage to his property, it would also be a less-reliable waste-disposal system.

Depending on which approach is taken—gravity pumping or horizontal drilling—areas that would need repair would include the driveway, courtyard and patio.

"A significant concern is the impact on the two mature oak trees in the courtyard area," Martire stated in the letter. "The proposed sewer-line trench would intrude on the trees' root area."

In addition, his letter states that the pumping system can fail due to a number of reasons such as blockages caused by foreign objects and normal wear and tear of the electric motor, causing "raw sewage discharge on the surrounding ground."

According to Assistant Engineer Morgan Kessler, sewer systems and treatment plants are much more thorough than septic tanks. At treatment plants, sewage goes through a series of mechanical, chemical and biological breakdowns. The products—filtered water and solids—are delivered to different places: the water is washed with chlorine to kill any remaining bacteria before it hits the bay, while solids are eaten by bacteria and converted to less-harmful products. For septic tanks, contents go through similar processes but to a lesser degree.

"On average, each household uses approximately 350 gallons of water per person each day," he said. "Imagine all of that water going back into the property's backyard."

The city's decision as to whether to include the 15 properties in the septic abatement program will be dependent on the results of the creek-water test. The issue will be discussed at a city council meeting in late October.