Texas requires municipalities to have a backup power system that will last two weeks for all water/sewage plants.
A Texan who gets their water from the city will have two weeks to put some up for later.
I also have a bag of sakrete to plug my sewer line to prevent backup into the house when the sewage lift stations fail.
You can't depend on the water plant to have potable water for two weeks. Houston water was polluted after Ike hurricane went through there, so there was no city water to drink. In my town, one of the water stations flooded with flood water and took out the backup power generator.
You can't depend on ANY outside service working after a natural or manmade disaster. After Ike took out power, the hospital switched to their generator and it wouldn't work. There was no one to work on it as those people were home with the family during and after the hurricane and the only phones that worked were those that plugged directly into the wall. Critical patients were driven to San Antonio, a five hour drive. No operations could happen no matter how critical the operation was.
Due to phones not working except those that plugged directly in the wall, no one could call 911 if they needed to and if they had gasoline in their car and went to the emergency room, they had light from a small generator but could only do minor medical procedures as no one could be checked in to the hospital. Patients were left in their rooms in the dark and it was hot summer.
The best way to prepare is to assume there is no power and won't be and no utilities will work and there won't be any gasoline to buy. There was no gasoline for many miles in all directions from Galveston through my town and on to Huntsville. There was no power to get the gasoline out at a station but it didn't matter because the pumps were pumped dry.
No food returned to town UNTIL gas stations had gas as food trucks could not refill their gas tanks so they didn't come.
The last food item to come back was bread after the other food was already back.
I am on the high side in the immediate area where I live and the sewage will fill up those on the lower side before it gets to me and I know where the sewage cut off is not many steps from my front door. You are doing good to think of sewage because most people don't.
Sounds good. We’re on septic, and we keep it healthy.
“two weeks for all water/sewage plants”
Extremely unlikely to happen. Definitions of what constitutes the water supply, the cost of fuels, mechanical breakdown, etc. all say you’ve got but a few days at best.