Fire Protection Drain to Sewer?

Mepsuper--

I don't know the reference you seek. However, I believe it is because the discharge of the fire sprinkler system to the sewer line is representing an increased flow which is adding to the treatment plant's total load and thus increasing costs of operating the utility. A bigger but similar problem is caused by connecting storm drains and roof drains to the sewer lines and by the infiltration of ground water or runoff water into the sewer system. When the municipality has a particularly large flow, the treatment plant's capacity is exceeded and they either have to retain the extra volume in a basin or other structure or let it bypass the plant and be discharged with little or no treatment. If this happens very often, then the municipality will start looking at adding more capacity and charging increased bill rates to pay for it. Any discharges of untreated sewage will end up in navigable waters and must be reported to the state and or federal officials. If there are too many, they can be fined and ordered that they fix the problem. Managers have lost their licenses and their jobs if they cover up or fail to report these things.

Therefore, the waste treatment people try to minimize all sources of unnecessary flow. Once again, I don't know the actual code reference. It may not exist. It may be in the rules the utility has regarding what can or cannot be connected to its treatment system.

Regards--John M.

The uneven distribution of flow by firefighting or storm water is a real problem.

The main problem however is that chemicals used in, or produced by firefighting may be detrimental to the water cleaning process.

Foam is designed to keep oxygen out but oxygen is required to degrade the sewage.

etc.

The drain is not to be tied to a sewer drain directly due to AWWA (American Water Works Association) guidelines that are adopted by law or code in many locales. Tying a drain from a fire sprinkler system directly into a sewer drain creates a potential cross connection that can compromise a water purveyor's supply via cross contamination. The drain can be run near a floor drain, but an air gap must be utilized, and typically the gap is 2 times the diameter of the drain pipe. If the floor drain is tied into the city sewer, that's another issue that a building inspector should have caught prior to the install of the fire sprinkler system, unless local plumbing codes allowed that at the time of original install.

In this case we will or do have designed "air gap" between the sewer drain and the sprinkler. Our initial design intent was to drain to daylight and not connect to the sewer. Unfortunatly the Engineer of Record had written the field change directive requesting the sprinkler line to drain to the sewer "Mop Basin". The requested change to the original drawings was made to clearify this intent and unfortunatly it was overlooked.

This has been helpfull.

That sounds similar to condensate drains from cooling coils in ceiling HVAC equipment. They cannot be connected directly to a sewer line because during the heating season, when the cooling coils are not generating condensate, the "P" traps would dry out and sewer gas would vent up the line eventually to the occupied space. Consequently they are commonly run to drain to a mop basin (sink) in a janitor's closet.

As the fire sprinkler system is having 100 to 150 psi pressure the water which is there in the line gets contaminated & after a time its harmful . it could affect the bacteria in sewage treatment result in loss of efficiency .