Q: I live in an older home with the original plumbing fixtures. I slowly want to change out and update everything to water-saving fixtures, but don’t know where to start. What do you recommend I replace first to start saving water?

A: What I’ve learned in my years of replacing residential plumbing fixtures is that an older toilet is a good place to start — especially one that is in poor condition or wastes a lot of water per flush. I’ve noticed that many homes are still using older toilets, so you’re not alone.

Before you purchase your new toilet, make sure you check your local codes and water restrictions. This can help you decide on which type of high-efficiency toilet to get.

I have worked with three popular high-efficiency flushing systems.

Tower flush. This is a gravity flush system that uses a cylindrical tower in place of a more common flapper setup.

Air assisted. A compressed pocket of air trapped in a sealed tank helps power the flush.

Dual flush. These toilets have two flushing choices: a full-flush setting for solids and about a half-flush for liquids.

Ed Del Grande is a master plumber, contractor and author. Send questions to eadelg@cs.com.