North Texas survival trip

My kid and I will be testing our skills with minimal gear for 3 days and I'm curious what others do in this region to purify water quickly without carrying filters.

North Texas water? You don't purify it, you just add more Tabasco sauce . But seriously, solar stills are your best minimalist friend and good luck to you and the kid!

North Texas is a huge area. Amarillo to Texarcana. Where about?

Cool idea. I have wanted to try this with my friends, but they are too soft.

Boiling water is the old school cowboy way. Notice the tripod and the big pot hanging over a fire you see in some cowboy movies? That is the drinking water. The movie people don't seem to know what is in the pot but they know it was part of camp as seen in old drawings and books.
Do you allow a cooking pot on these trips?

When I was a kid, it was boiled water poured through a paper towel for that special pond water taste.

SODIS in clear bottles is a good backup if it's sunny but won't filter out chemicals or cloudiness.

Boiling water for one minute kills most germs, you can also carry chlorine tablets or unscented bleach for quick cleaning

There is a bleach generator I saw in am Air Force SERE training for purifying water in the bush. It was very small and produced a very small amount of bleach but enough to kill the nasties, I always carry a SteriPen UV water purifier, small and light. One of mine id rechargeable and a small solar panel works for that or other small electronics, I use it mostly when traveling to other countries. A small fold of cheesecloth works well to filter out sediment, nice to have regardless of your other method.

MSR MIOX​

They work great BUT it is too easy to screw up.
It is not "GI Proof"
MSR discontinued them several years ago.

Not for survival training but there is a water purifier that utilizes the same chemistry as the MIOX but on a larger scale. It requires a 12 volt car battery and table salt.
https://swimforhim.org/
Safe Water International Ministries
They changed up the website so I have not found the link to buy the device. It is still $100 as far as I can tell.
Mine works great and can produce enough chlorine for many people.

Firstly, a tip of the hat to you sir for taking the time to give your kid an experience like this. Kudos to the bonding & resilience your instilling in them.

Here's a couple considerations:
1. Boiling is the most effective to kill any/all pathogens. A "rolling boil" for at least a minute should do it (a couple minutes even better). However, as someone noted above, boiling doesn't remove heavy metal / environmental toxins. You'll need a filter for that.

2. Chlorine tabs, liquid Chlorine bleach, or Iodine tabs. These are convenient, but only kill off bacteria & viruses (& maybe some protozoas like giardia). But, none of these are effective against protozoas like Cryptosporidium. And not effective against heavy metals / toxins. For these, follow the instructions on the bottle, or for liquid bleach use this website as a guide for ratios based on % chlorine in the bleach. ((And make sure its just plain 'ol bleach; nothing scented, 'color safe', etc)).
https://www.epa.gov/ground-water-and-drinking-water/emergency-disinfection-drinking-water

For Iodine & chlorine, you'll need to let it sit for at least 30 minutes before drinking, so if crossing a stream fill up your empty canteens & use appropriate doses so it's doing its thing while continuing your trek.

3. Cloudy water will take more time & resources to purify, so filtering it thru a thin cloth with charcoal can help remove some of the cloudiness & improve tase.

4. If you're going to be stationary for a day or two, the solar still will be a cool experiment to try. It doesn't produce a ton of water, so you may want to dig a couple of them. Some plants will make the water taste funny, so after producing the clean water may want to run it through a charcoal filter as well.

4. UV pen lights kill pretty much everything, but nothing for heavy metals / toxins. If the water is cloudy, or you don't stir it up enough, you may not kill all the bad stuff, so either filter first, or wand it longer. ((Also get from a reputable place; REI may be more expensive, but more peace of mind than Amazon...)

5. Filter systems. Look for something in the .01 micron range so it gets all the nasties, plus most of the heavy metals. And carry extra filters. Cloudy water will reduce life span, so clarify first if possible.

6. Med Intel. Look at what's upstream / uphill of your water source, & take that into account for what you'll need to filter out. If your water source is downstream of a pig farm, chicken farm, hay fields, solar farm, industrial sites, etc, your method of purification will need to account for what may be in the water. ((Also take into account other environmental factors, like if you're staying at a primitive campsite where people have been deficating on the ground / cat holes / slit trenches, there may be other hygiene issues such as pinworms in the soil))