Frequently Asked Questions

A cross-connection is any temporary or permanent connection between a public water supply or consumer's potable (i.e. drinking) water system and any other source containing nonpotable water or other substances. An example is the piping between a public water supply or consumer's potable water system and an auxiliary water source, cooling system, or irrigation supply.

Backflow is the undesirable reversal of the flow of nonpotable water or other substances through a cross-connection and into the piping of a public water system or consumer's potable water system. There are two types of backflow: backpressure and back siphonage.

Back pressure backflow is caused by a downstream pressure that is greater than the upstream or supply pressure in a public water system or consumer's potable water system. Backpressure (i.e. downstream pressure that is greater than the potable water supply pressure) can result from several things: an increase in downstream pressure which can be created by pumps, temperature increases in boilers, etc; a reduction in the potable water supply pressure which can occur whenever the amount of water being used exceeds the amount being supplied, such as during water line flushing, fire fighting, or breaks in water mains; or a combination of both.

Back siphonage is backflow caused by a negative pressure (i.e. a vacuum or partial vacuum) in a public water system or consumer's potable water system. The effect is similar to drinking water through a straw and can occur when there is a stoppage of water supply due to nearby firefighting, a break in a water main, etc.

Backflow into a public water system can pollute or contaminate the water in that system (i.e. backflow into a public water system can make it unusable or unsafe to drink), and each water supplier has a responsibility to provide water that is usable and safe to drink under all foreseeable circumstances and must take reasonable precautions to protect its public water system against backflow. Furthermore, consumers generally have absolute faith that water delivered to them through a public water system is always safe to drink.

Water suppliers usually do not have the authority or capability to repeatedly inspect every consumer's premises for cross-connections and backflow protection. Alternatively, each water supplier should ensure that a proper backflow preventer is installed and maintained at the water service connection to each system or premises that poses a significant hazard to the public water system. Generally, this would include the water service connection to each dedicated fire protection system or irrigation piping system and the water service connection to each of the following types of premises:

• Premises with an auxiliary or reclaimed water system
• Industrial, medical, laboratory, marine or other facilities where objectionable substances are handled in a way that could cause pollution or contamination of the public water system
• Premises exempt from the State Plumbing Code and those where an internal backflow preventer required under this Code is not properly installed or maintained
• Classified or restricted facilities
• Tall buildings. Each water supplier should also ensure that a proper backflow preventer is installed and maintained at each water loading station owned or operated by the water supplier

A backflow preventer is a means or mechanism to prevent backflow. The basic means is an air gap, which either eliminates a cross-connection or provides a barrier to backflow. The basic mechanism is a mechanical backflow preventer, which provides a physical barrier to backflow. The principal types of mechanical backflow preventers are the reduced-pressure principle assembly, the pressure vacuum breaker assembly, and the double check valve assembly. A secondary type of mechanical backflow preventer is the residential dual check valve.

An air gap is a vertical, physical separation between the end of a water supply outlet and the flood-level rim of a receiving vessel. This separation must be at least twice the diameter of the water supply outlet and never less than one inch. An air gap is considered the maximum protection available against backpressure backflow or back siphonage but is not always practical and can easily be bypassed.

An RP is a mechanical backflow preventer that consists of two independently acting, spring-loaded check valves with a hydraulically operating, mechanically independent, spring-loaded pressure differential relief valve between the check valves and below the first check valve. It includes shutoff valves at each end of the assembly and is equipped with test cocks. An RP is effective against backpressure backflow and back siphonage and may be used to isolate health or non-health hazards.

A DC is a mechanical backflow preventer that consists of two independently acting, spring-loaded check valves. It includes shutoff valves at each end of the assembly and is equipped with test cocks. A DC is effective against backpressure backflow and back siphonage but should be used to isolate only non-health hazards.

A RDC is similar to a DC in that it is a mechanical backflow preventer consisting of two independently acting, spring-loaded check valves. However, it usually does not include shutoff valves, may or may not be equipped with test cocks or ports, and is generally less reliable than a DC. A RDC is effective against backpressure backflow and back siphonage but should be used to isolate only non-health hazards and is intended for use only in water service connections to single-family homes.

Mechanical backflow preventers have internal seals, springs, and moving parts that are subject to fouling, wear, or fatigue. Also, mechanical backflow preventers and air gaps can be bypassed. Therefore, they have to be tested periodically to ensure that they are functioning properly. A visual check of air gaps is sufficient, but mechanical backflow preventers have to be tested with properly calibrated gauge equipment.

• The University of Florida TREEO Center maintains a Backflow Prevention and Cross-Connection Control Program Page
• The American Water Works Association’s Manual M14, Recommended Practice for Backflow Prevention and Cross-Connection Control, telephone 800-926-7337
• The University of Southern California’s Manual of Cross- Connection Control, which is available from the Foundation for Cross-Connection Control and Hydraulic Research, telephone 213-740-2032

A Precautionary Boil Water Notice is a public notification issued by the City of Lake Mary advising customers to boil water before consuming it. A Precautionary Boil Water Notice is only issued after careful consideration by the City and the applicable regulatory agencies as a preventative measure to protect public health.

Boil Water Notices may be issued because of water system loss of power, loss of water pressure, a water main (pipe) break or other unforeseen emergency. The notice does not mean that the water is contaminated, but it is possible for impurities to enter the pipes and affect drinking water. As a precaution, it is important to disinfect tap water before consuming it to kill any impurities or use bottled water.

There are two simple and effective methods you can use to treat drinking water to remove impurities.

• Boiling: Bring the water to a rolling boil for at least 1 minute.
• Disinfecting: Liquid chlorine bleach (unscented) can be used at a dose of 8 drops (1/8 teaspoon) per each gallon of water. Let stand for at least 30 minutes before use. If water is cloudy use 16 drops (1/4 teaspoon) per gallon of water.
• Use boiled or bottled water for drinking, food preparation, mixing baby formula, making ice, washing food, manual utensil and equipment washing, rinsing and sanitizing, brushing teeth or any other activity involving the consumption of water. Pets should also be given boiled or bottled water.
• Child care centers and schools should use only bottled or boiled water for mixing infant formula, hand washing and for mixing sanitizing solutions for diapering areas and surfaces such as tabletops and toys. Adult employees should use a hand sanitizer after washing hands with tap water and soap. Do not use drinking fountains.
• Retail food establishments must follow the guidance of the local Health Department.
• Other businesses and non-residential sites can help inform the public by posting notices at or disabling water fountains and ice machines during the Precautionary Boil Water Notice. If water is provided to visitors or employees, use commercially produced bottled water for drinking or beverage preparation.

Until tests results show the water is safe to drink, you should not drink the water without boiling it first. Although waterborne diseases are extremely rare, chances are if you are in good health, you will not get sick from drinking the water. The risk is higher for infants, some of the elderly, and people with compromised immune systems. They should not drink the water until it is deemed safe to drink. If you have specific medical concerns it is suggested that you seek advice from your health care provider.

Most home filters are designed to improve the taste and/or odor of you water, not remove bacteria. Check with the manufacturer for more information regarding your system. As a precaution you should boil your water or use commercially bottled water even if you have a filtering system.

The water is safe for washing dishes, but you should use hot, soapy water and rinse dishes in boiled water. You may add a tablespoon of bleach per gallon to the wash water. You may use a dishwasher if it has a sanitizing cycle. There are no restrictions for doing laundry. Water may be used for taking showers or baths, as long as care is taken not to swallow the water or allow the water to be ingested. Use only disinfected or boiled water for brushing your teeth. Wash hands with soap and boiled water, or soap with bottled water. If only tap water is available, it is best to use an alcohol-based hand sanitizer after you wash your hands.

It will remain in effect until further notice from the City. This can be a minimum of two days while bacteriological tests are being conducted and repairs are being made to the system. The City will lift the Precautionary Boil Water Notice only after all laboratory tests confirm the water quality meets or exceeds all required drinking water standards.

A rescission notice will be issued by the City of Lake Mary. Customers are encouraged to stay tuned to local radio and television stations for updates. The City will post information to its website and signboards will display that the Precautionary Boil Water Notice has been lifted.

Flush the water out of your household pipes, water fountains, etc. prior to drinking or cooking with the water. Let cold water run through the pipes for a few minutes by opening several faucets throughout the house and outside faucets. If you have an automatic ice maker, allow it to make three batches of ice and then discard that ice. Any ice made during the notice should also be disposed of.