In the event of a drain back up or flood, the contents of the drain line should never be able to make contact with the water supply - the two plumbing systems (for potable water and for waste) should always remain separate.

Should they come into contact (a cross-connection), the potable water supply can be seriously compromised.

Contamination can occur in a backflow event, where either siphoning or a difference in pressure in the supply line can draw the contents of a directly-connected drain line into the clean water supply.

That space is between the fixture outlet and the flood level rim of a receptacle (be it a sink, floor drain, standpipe, or other approved unit).

Think of a faucet (outlet) and sink basin (receptacle): water that leaves the faucet flows across empty air into the basin.

Even if the basin were to stop draining and back up to its flood level rim (the top edge or the overflow), dirty backed-up water can never reach the faucet thanks to the space between.

Many are familiar with dishwasher air gaps, but there are other situations in which a direct drain connection might be prohibited, and an air gap necessary.

For dischargesupply pipes that are larger than 1 in diameter, the minimum gap distance is usually twice the pipes diameter (e.g.

But as explained above, its function is incredibly important: the rare backflow event that has the potential to move wastewater back through the drain hose and into the dishwasher is instantly neutralized with an air gap.

Most plumbing codes require an air gap on the RO drain line to prevent the possibility of contamination.

Annoying as this may be, we still recommend using an air gap with any RO system, even when not required by code.

Because theyre usually installed in garages, basements or utility rooms, softeners are typically drained into a floor drain, laundry sink, standpipe or a washing machine outlet box.

When floor drains or sinks are used, the softeners drain hosepipe can simply be secured above the receptacle following local guidelines for air gap distance.

Securing the line is important, as the softener discharge does exit with some force.

This device features a 12 inlet for the softeners discharge line as well as a 1-14 opening for standard washing machine drain hoses, allowing both fixtures to utilize the same drain.

Code typically requires they be discharged through an indirect waste pipe by means of an air gap.

Whereas the other fixtures weve discussed have uniquely designed air gap devices, these do not.

Instead, the discharge pipehose itself is merely secured at the proper height (likely 2x the diameter of the discharge) above the indirect waste receptacle to create the air gap.

We highly encourage the use of air gaps, even when one is not required by code (as can often be the case with dishwashers ).

When it comes to preventing contamination, theres nothing more simple or reliable.

Air Gap For Water Softener Waste Pipes