Absolutely correct about online advice! I know how youtube or other online advice is often very specific to the creator's region. It's best to connect with competent locals with decades of experience. Gardeners are very generous with hard won local knowledge and tips.

Being in an arid place, I keep a three gallon plastic bin in the kitchen sink to capture all dishwater. Several times a day, I carry it outside to water some lucky plants. It would be even better to get the shower and washing machine drainage to be plumbed such that more "gray water" makes it outside to the trees. Most soaps and detergents are pretty safe to vegetation nowadays.