I recommend my clients irrigatate as infrequently as the landscape will tolerate, yet when you do water, water deeply to the point of saturation. It may take a cycle/soak application method, but it is the most effective means of watering. I water once a week in my established landscape just north of Houston.

You should water around 10 to 15 minutes every other day or until you start to get runoff. water in the early morning this will allow more water to get absorbed and not to evaporate. If you have gear driven rotors you need to increase the run time.
Hope this helps.

Here is a link that might be useful: help_site

Hi texican,

This is a method that is easy and it teaches you about your whole system. If you have zones, do this for each zone.
First you need to apply one inch depth of water per week for plants. Different grasses have different requirements(use drought resistant varieties suitable to your area). Start out with the one inch per week rule and cut back from there until you see signs of stress or add more if needed. Place cups around the zone (you can decide the number) the more cups the more detail info you will have. Run your system for what ever time you think will give you 1/2" of water. Record the depths in the cups. Now you know the duration and depth relationship of your system. You also know the trouble spots or drier areas of your system. Using the drier spots as the design point, calculate the time your system has to run to get one inch of coverage. Spread that duration throughout the week to apply the water that is needed for healthy grass. The grass will tell if you are under-watering or over-watering and it will change through the seasons. One last very important aspect for lawns is aeration. The water will runoff and be wasted if it can't get to the roots.
Have fun
Aloha

I recently read that it takes 62 gallons of water to water 100 sq. feet of lawn to a depth of 1". This article suggested watering a half inch twice a week. Subtracting rainfall. The grass will grow shallow roots if you water 5-10 minutes every night and will have a weaker root system.

In short, water once or twice a week as deeply as needed. In spring you may not need to water much at all.

Best wishes.

Hi Texican,

Sage Lover comments are correct and I would like to look at SL comments a little differently.
1. All lawns have different soil. some are more porous than others and as grass grows and ages less water penetrates. That is why areation maintenance is so important. irrigating so there is not runoff is also important. Water that doesn't penetrate and runs off is costly and wasteful. Record the time it takes for your lawn to start running off. Divide that time into the total time it takes to get 1" of depth coverage and that is the number of time you irrigate per week. Improving the quality of soil depth and aeration will lengthen the time it takes before run off occurs and improve grass health greatly.
2. 1/12 ft x 100 sf = 8.33 cf x 7.481 gal/cf = 62.34 gals