I suspect most construction companies will ensure their workers get plenty of water. If only because people who drink enough water on hot days get a lot more done in the day.
This law means nothing in practice. If you are working construction in the Texas heat, you need to drink water every 10-30 minutes, not just once every 4 hours. I can't imagine an employer lasting long if they didn't allow their employees to drink water when needed (and visit the portapotty accordingly). When I worked construction in the summer in a place nowhere near as hot as Texas, I drank 1-2 gallons of water a day, and it wasn't just on a few legally mandated breaks.
Every construction site I've seen has a water cooler and the people are allowed to take a drink every time they walk by. Either that or the people all come to work with their own water which they bring with them all day to drink when they want. Nobody cares about the few seconds lost to someone having a drink.
