If you still have a lawn and want it evergreen, but using as little water as possible, just add clover. Hopefully, you’re already maintaining your lawn organically (no chemical fertilizers or herbicides or weed&feed) and grasscycling. If you look closely, you will probably find some clover there already, probably in the really green parts. If not, you can overseed any part of your lawn that is looking bare/brown/patchy with Dutch White Clover seed. You can also top with some compost for good measure, but no need to go crazy with stinky manure.
Clovers, like legumes, (and with help from their little friends, in the soil) pull nitrogen out of the air and bring it into the soil, where they share it with the grass. Free, natural, bio-available fertilizer. That’s why the grass growing with them is super healthy.
You can order seed online (it’s cheaper than fertilizer!), and just scatter some around your yard, especially where it’s looking unhappy. Water it regularly for a week or so and watch your grass turn super (lucky) green.
Read more about this in the “Estate Lawn” section of the Beverly Hills Garden Handbook.