sound like the sprinkler system and house water are on the same line. Outside of pressure issues if there's no backflow preventer you run in to other issues. Find a good & affordable person versed in well systems or irrigation place.

They can split the system off at the well to run 1 to house and a separate feed for sprinklers.

Ours is set up on 2 different feeds, or we'd be dealing with the same thing.

regarding the sulfur smell. You did have the well tested prior to purchase, yes? Just because there's pressure and a good flow, doesn't mean there's ecoli or other contaminate in the system

http://wellwatertalk.com/microbes-in...li-well-water/


There are many ways that coliforms can enter your well water. Heavy rainfall, spring runoff, and flooding events are often high on the list of causes – overwhelming even newly-constructed wells, and introducing surface contaminants, including e.coli, into the well. If you have an older well, there are even more potential avenues for surface contamination (including coliforms) to enter your water.