My rainwater catchment “system” is super basic, about as simple as you can get: just barrels and stock tanks lined up under the roof line. I have done extended experiments where I live on just rainwater, which I scoop out of the barrels with a pitcher or saucepan (though my house is a normal urban house hooked up to city water).
I live in a part of Florida where we rarely get a freeze, let alone a long deep freeze – but we never know when one could hit here too, huh! Encouragingly, many of my friends in Texas who have rainwater collection found that their water didn’t freeze solid even during the recent multi-day siege of subfreezing weather.
Rainwater catchment is a useful and simple way of maintaining household fresh-water supplies during extraordinary weather events and other disasters of all kinds. Rough rule of thumb: A 1,000-square-foot house can collect up to about 600 gallons of water off its rood from a 1-inch rain.
Dealing with mosquitoes: It’s actually not hard. I simply keep the barrels covered when they are not actually being used to collect rain. Another reason I keep my barrels and tubs covered is so insects, lizards, and other local critters will not be in danger of falling in & drowning.
My simple setup collects and stores a total of about 500 gallons. But you can get started collecting lovely fresh water with even just a single barrel, or even just a line up of large pots, pans, buckets under your roof line.
Filtering/treatment of rainwater for emergency use for drinking and cooking: Many types of homescale filtering systems are available. The simplest and most popular I know are the Brita and the Berkey.
Rainwater collection is like money in the bank. It gives you, your household, and your landscape a natural buffer against disasters and against increasing drought-flood extremes.