ms,

What is you pressure and flow rate without the irrigation on? Do you need help to find this out? What is the pressure with the irrigation on? How is your irrigation system configured in relation to the house and the booster pump? What is the rating of the booster pump? Do you know your peak flow usage of water during the day? Your average daily usage would be your monthly water bill use divided by the days. The irrigation total is the number of heads times the flow rate per head. My thought is sizing a tank that gets used during the day and fill up at night. My other thought is redo the piping for the booster pump to feed the tank or house instead of just for the irrigation line branch. You would have stronger pressure in the house when you are irrigating. JMHO Aloha

You might look into the water service line coming from the city's main to your house. It is possible that 1) it is badly clogged inside from corrosion and mineral deposits 2) it is undersized for what you need, say 1/2 or 3/4" possibly. 3) your water meter is preventing full flow.

How is your flow and pressure in the house when you run more than one tap at full force at one time, I.E. do you get a sudden drop in flow and pressure? That can be caused by an inadequate service line or the design of your indoor plumbing.