On 7/9/2017 8:41 PM, Stormin' Norman wrote:
On Sun, 9 Jul 2017 20:32:51 -0400, Ed Pawlowski wrote:

On 7/9/2017 5:49 PM, Stormin' Norman wrote:

I am not sure if plumbing code in all states require an air gap as
part of the dishwasher installation. For more information, see:

https://www.thespruce.com/dishwasher-venting-2718654


Air gaps are not required in AZ unless in certain commercial buildings
and high rise apartment buildings.

That is interesting Wayne, thanks. If it were me and if I had an
extra punch-out in the sink, I think I would install one regardless.


I wouldn't, just a loop. Had dishwashers for 50 years and no problems
without it. Anyone know of a problem actually caused by a DW that back
siphoned into the water system? Yes, it can get into the DW, but the
purpose of the air gap is to protect the domestic water supply.

The air gap with a dishwasher prevents drain water from backing up
into the dishwasher and contaminating the dishes. Doesn't happen very
often, but if it does happen it can make people quite ill.

Not sure how a dishwasher air gap would protect the potable water
supply, but maybe.


That is the purpose of it. Id pressure drops while the machine has
water in it, there is the possibility water can siphon back to the water
supply. Same reason backflow preventers are required for sprinkler
systems and some towns want them on every residence. Overkill, IMO. I
can see it in industrial settings. Our boiler feedwater systems have to
have them but we're talking 125 psi pressure if the power went out to
the city system.