The evening before the storm hit I phoned my son in Guaynabo to make sure he was prepared. First floor of a 3 story concrete building and facing away from the south—check. Plenty of bottled water and food—check. Bottle of regular not fancy bleach—check. [Note: 1/8th teaspoon of bleach in one gallon of clear water, let it sit for several hours. If cloudy or muddy, filter through a fine cloth or coffee filter. Double the dose if still cloudy. Don’t use fancy scented or other “special” bleach.] Nearby stream to get water—check. I texted him after the storm and a day or two later he texted, “We are OK.” Text needs less power/bandwidth or whatever. He has phoned my US living son twice, and 3 days ago reported municipal water restored. When my husband was dying of Alzheimer’s at home, I built up a 3 month supply of food in case it was hard to go out in the last months. Fortunately, he was only non-mobile for 1 month at the end. I have read 2 novels on EMP type situations in the US. Really scary stuff.
I bought a set of 3 water filter systems, really cheap but will take water from a puddle and with a simple pump give you drinking water. With a pack of filters, would last a person a month.
You could also buy water purification tablets, we used them back in the day in boy scouts, a little easier than hauling bleach around, and about as effective. bleach though is good as a last-resort cleaning solution for cuts and scrapes, if you didn’t stock up on some tubes of antibiotic ointment.