They are mandatory to prevent water from hose backing up into house water. If you plan on selling the house at any point, you will need to replace them if you have removed them.

"Back Flow preventers are devices that are often times added on to the end of a hose spigot. The purpose of a backflow preventer on a garden hose spigot is to prevent tainted water from entering the drinking water system. Let me explain it like this: If your neighbors house is on fire and there are firemen using fire hoses to put it out, the amount back pressure needed could actually suck the dirty water out of the bucket your using to wash your car. If there was no back flow preventor on the line our clean drinking water could be compromised. That is why they have made it code to have a back flow preventor on your hose spigot."

I have had them on our house for over 10 years and never had a problem shutting off the water.

“I know these are code but…”. Those words tells me you’re looking to violate some government law or ordinance. I’m actually stunned by the number of people here who don’t believe the laws apply to them. See the posts on how to make carts go faster than 20 mph, or which complain about people going the speed limit on our 35/45 mph roads, or advocate for lawn ornaments which clearly violate community standards and deed restrictions, etc etc.
And it seems more and more of these posts contain threats directed at anyone who might challenge them for their actions. All these things add up and will ultimately ensure that The Villages becomes a city rather than a Community. Please stop.

The same principle applies to all faucets in your house. That is why the faucet outlet is located above the overflow level of the sink. But, if you connect a hose to a faucet, like the laundry tub, you can contaminate the water if it backs up into your house.

People and codes-laws. You will find it is the same people, plumbing, special parking, dogs, golf cart speeds, vaccines etc etc etc. Oh and name calling

Death from drinking water
 

There is a safety reason. Years ago a person was spraying insecticide with a hose attachment. Put the hose down and went inside for a glass of water from the kitchen. Got sick and died as the poison back flowed into the house and he drank it.

Death happened from insecticide.
 

Death from insecticide

when standard hose bibs are outlawed, only outlaws will have standard hose bibs
now I wish I hadn't removed that mattress tag

[ATTACH][/ATTACH]I created my own shield that prevents me from getting a shower every time I use the hose. I’m trying to post a photo.

When I installed a backflow preventer on my hose bib, I did not tighten the set screw so it can easily be removed. That screw has no functional purpose other than to try to prevent removal of the backflow preventer. If it fails, you need to either replace the entire valve or start drilling! I know that many homeowners have no idea that such a device is required by code.

Not sure why code can dictate such things but not require hose bib manufacturers to make their products with built in backflow preventers. That's probably coming...

………

what is that you used and how did you connect it to the faucet?

The reason it sprays you is that the little rubber goodie inside that's suppose to prevent back-flow probably rotted and quit working about 3 years after the house was built. They don't spray like that when they're new.

It's a really useless device, designed primarily to make rich the guy who invented it and then convinced some bureaucrat to force you to buy it. Think about it -- in order for some nasty bug to sneak from your hose all the way into your stomach, it has to somehow get past a closed hose bib valve, or swim upstream a distance equivalent to you walking to the moon -- only it has to swim through chlorinated water designed to kill it.

The uselessness of this device explains how hundreds of millions of people somehow survived hose bibs prior to the invention of the backflow preventer -- and still do, in places where they aren't required by code.