new grass needs to be given an inch of water a week. Newly laid grass needs to be watered up to four times a day for the first month and then gradually decreased to provide and inch of water a week. For me that is about 45 minutes total. I usually do that 15 minutes every other day. Bermuda grass and zoysias go dormant in summer. It is how they respond to drought conditions. They will be more yellow and not a rich dark green unless you really throw a lot of water at them.
New grass should also have had organic matter worked into the soil before you planted it and given a starter fertilizer. Fertilize monthly and don't mow for three months. Summer grass should be mowed about an 1-1/2 inches. In cooler months you can go down to 1 inch. After the first year, I only fertilize with mostly sulfate of ammonia and I dethatch, aerate and topdress at the same time twice a year, once in the Spring and again in the fall (March and September).
You can tell if your grass is getting enough water. When you walk on it, it should not feel crunchy and if you can see footprints and the grass does not spring back, you have not watered enough.
Bermuda grass is not popular here because while it is a very nice looking grass, it has a lot of issues with showing weeds, armyworms love it, and it gets fungal diseases if it gets too much puddling issues.
Brown can be dead grass from not enough water, but brown spots can also be army worms chopping on the grass.
In the early evening go to a spot near the edge of the brown area and use a hose and flood it. If there are army worms there they will come to surface so as not to drown. You can pick them off that way.
I have dwarf St. Augustine grass, it hides nut sedge well and is not attractive to lawn pests. It is also good in shade and wet soil so it does not have a lot of issues with fairy rings.
Zoysia is also a tough grass that competes well with weeds and crowds them out, but they do form tufts that need to be kept trimmed and you should use a reel mower not a cheap rotory mower on zoysia. It grows slowly so takes a while to fill in but slower growing zoysias do not need to be mowed as often. Zoysia is also another grass that has tough blades that are not that attractive to army worms.
Seashore paspalum is good for sandy soil, grows fast and looks nice, but it is inappropriate in a wet area and heavy soils where it will be prone to fungal diseases and fast growth makes it attractive to lawn pests.
El toro is popular among the landscapers. It is an easy grass to put in, looks nice, and grows fast. it keeps them in business because it needs to be mowed every week to look good, otherwise if not mowed often it can get pretty shaggy.
It is a medium blade zoysia that is drought and traffic tolerant once it is established.
Grass is probably the biggest water hog of all plants. If you want to save water, plant in the cooler months when you may get some help from mother nature watering and there is less evaporation. Grass will grow slower but the roots will be better established before the hot weather sets in. Minimize grass and only plant it in areas you really need it.
Happy gardening in Hawaii. Gardens are where people grow.