If you refer to watering your lawn, I personally would not do it. Unless it is newly seeded or recently put in sod. Grass is a monoculture, really, and quite tough -- it goes through natural brown cycles in summer, and recovers well afterwards with cooler weather, when you could resume watering. As this is what I do, someone else will have to answer your question!

Save your water bill - or your well water! Let it be.

=)

Almost impossible to answer. Cool season grasses - what you would have in Maine - naturally want to go dormant in summer, focusing their growth during the cooler times of the year. You can allow them to do so, as per roxanna's suggestion, and they will recover as soon as the weather cools and fall rains arrive.

If you don't want the brown appearance of a summer dormant lawn, you can water of course. It will need between 1 to 1.5 inches per week, best delivered all at one time rather than for a short period each day. The key words are infrequently, slowly and deeply.

If you also run a sprinkler system on any planting beds, that is a completely different issue.

I assume you have already evaluated the reliability of your water source. In the northeast, almost all the piped water (well or reservoir) comes from the same rain that is, or isn't, falling on the garden. So an extended drought can have a significant effect on the amount of water available. Watering plants, then cutting off the supply because the well is going to run dry, etc. is where the real death and destruction happens. If you don't water, most plants will just go dormant, or otherwise adjust. It's hard to put down enough water to encourage plant roots to go deep enough that they can survive on their own if they have to.

The last time we had a serious drought, the village north of us had their wells go dry. They were trucking in water for drinking, and the flowerboxes in front of the post office had a little sign 'Watered with water from the Hudson River', which was down the road about a mile. Since then, they have added an emergency tie in to my water company, as has the larger village south of us. We have never had water problems, but if everybody starts relying on our wells, that will probably change.

I only water the serious divas, like Annabelle hydrangeas, and a few things in pots. Of course I cheat with some water hogs and plant them where the water table is only a foot or two down.

I only water newly seeded grass, never established, mature grass.
I always water my 3 Helleri bushes in hot weather (I love them!). The trick to protecting mature grass roots is not cutting your grass too short. We always use the mulcher on our lawnmower too, so the nutrients go back into the grass roots. Our lawn usually looks quite good too.

This is what I've been saying on this forum for 15 years.

Watering: Deep and infrequent is the mantra for watering. This is for all turf grass all over the place. Deep means 1 inch all at one time. Put some cat food or tuna cans around the yard, and time how long it takes your sprinkler(s) to fill all the cans. Memorize that time. That will be the time you water from now on. My hose, oscillator sprinkler (full sweep) and water pressure takes 8 full hours to fill the cans. Your time will likely be less. I like gentle watering. As for watering frequency, that depends on the daytime air temperature. With temps in the 90s, deep water once per week. With temps in the 80s, deep water once every 2 weeks. With temps in the 70s, deep water once every 3 weeks. With temps below 70, deep water once a month. Note that you have to keep up with quickly changing temps in the spring and fall. This deep and infrequent schedule works in Phoenix and for the most part, in Vermont, so it should work for you. The reason for deep and infrequent is to grow deeper, more drought resistant roots and to allow the soil to dry completely at the surface for several days before watering again. If it rains, reset your calendar to account for the rainfall.

So that's what I've been saying. The idea of this schedule is to keep the grass green and not allow it to go dormant in the summer. Here is a picture of some Kentucky bluegrass lawns in eastern Pennsylvania photographed in July many years ago. All four lots have the same grass.

The owner of the green lawn is one of the gurus on another lawn care forum. He has asked around and watched what his neighbors do as far as fertilizing, mowing, and watering. He says the main difference is that the other lawn owners water every day in the morning while he waters only once per week. I can tell you the same picture could be bermuda grass watered daily versus once per week. Deep and infrequent is the mantra for a reason.

Although I don't disagree with anything in these comments, I would add that soil type and grass type is a consideration. Sandy very well draining soil, does require less water and a bit more frequent. The idea is to "teach" the roots to reach deep for water but if the soil doesn't retain water, that is a losing proposition.

At my condo complex, they do horrible job of watering. 3x a week for 17 minutes each. The soil is mostly crappy. I have learned to lower my standards and pray for rain.

At my former house I would use a moisture meter and really try to determine the soil moisture before and after watering, trying to measure moist soil 4" deep. I marked the moisture meter stick accordingly so I could know how deep to insert it. Here at the condo, after watering, the moisture meter reads dry 1" down. ugh.... wasteful. And our water bill is HUGE.