Eat less meat: growing all that roughage into a chunk of meat uses a lot of water.
Use our electronic devices for much longer before replacement: silicon processing, for one, uses a lot of water.
Shower less often: anecdata, but here you go: I haven't taken a shower for more than a month (except once briefly to rinse off with tap-cold water, no soap, after I cut my hair), using more-natural (baking soda, bacteria) deodorant (packaged in cardboard, no plastic) in "pits and privates". No, I haven't lost my sense of smell yet (as vaccinated against COVID-19 as I can be so far, and cautious--protecting my under-five child who has enough challenges as it is, and yeah, I'm concerned about lack of socialization with peers), and I don't like wearing smelly shirts (so I think I can tell when I stink). Diet plays a role (I'm practicing going longer without eating; helpful in many ways), as does amount of exercise--I'm not regularly working up a sweat (and there might be long-term consequences for that) but I am regularly moving throughout the day, and lifting "heavy objects" (my child).
It's past time we cut back on so many luxuries and stop living like the royalty we think we are (I think I'm aware of how good I have it, relatively, and am actively adjusting to living a healthy, fulfilling life on fewer resources--please start running this lifelong marathon with me).