Dear Craig,

Thank you for contacting us about your HOA lawn. Most turf grasses have roots that are approximately the same depth as the foliage is tall. That is one reason we recommend mowing at a higher level: The roots growth balances out with the foliage, so cutting too short makes for more shallow roots. 

Some years ago, clover was mixed into lawn seed routinely. Then, with the invention of selective herbicides, broadleaf plants like clover were eliminated in lawns. 

Clover, as you may know, fixes nitrogen in the soil. This can reduce the need for nitrogen fertilizers; however, in order to make use of that nitrogen, the cuttings need to be left on the lawn. If you collect and dispose of them, the nitrogen goes with it. 

In answer to your question, your water savings will depend on the mowing height, frequency of irrigation, and temperatures which effect the evaporation rate. One advantage to over-seeding with clover is that it usually stays green in heat in late summer when turf grasses go dormant. This is generally when lawns are watered most often. Clover also creates more shade than grass, helping to slow evaporation from the soil. It's like adding a nitrogen mulch which will help improve the soil. (A common misperception is that leaving the clippings causes thatch. Thatch is actually caused by a combination of dead plant roots, poor drainage, poor aeration, and compacted soil.) 

There is now a new type of clover on the market that is called mini-clover. I am not sure where it is available, but it is said to have a much finer texture than traditional Dutch white clover. It does not grow as tall or as fast. You might call garden centers near you to see if it is available. 

This publication may help you maximize the efficiency of your irrigation program: 
https://extension.oregonstate.edu/catalog/pub/ec-1638-efficient-lawn-irrigation-intermountain-west

I hope this information is helpful. Please write again anytime you have questions.

Attn Lynn Marie …….