Behind the Walls: How Does a Shower Work?

Unless you’re a plumber or a talented DIYer, you probably haven’t given much thought to where the water in your shower comes from. The water comes through a pipe and out of the shower head, right?

Technically, yes. But it’s far more complicated than that, especially if you have a multi-function shower head or system. Curious about what goes on behind the walls of your shower? Here’s a simplified guide to how your shower works.


The components

When you’re installing a shower system, you will need (obviously) piping behind the wall intended for the shower, various hardware behind the wall (known as “roughs,” “valves,” “rough-in valves” or other similar terminology), and the fittings that are visible in the shower itself, such as the shower head(s) and control (called “trim”).

Depending on your shower configuration, you will need different types of plumbing and roughs. The trim must be compatible with the rough.

For simplicity’s sake, we’ll use the comprehensive illustrations from Hansgrohe (featuring the iBox, their universal all-in-one expandable rough) to demonstrate the inner workings of the shower.


This classic, simple configuration features one wall-mounted shower head and a pressure balance valve. Water flows from the hot and cold pipes into the valve, where temperature is regulated before the water travels through a single pipe to the shower head.

The iBox makes it easy to upgrade from pressure balance to thermostatic, or to add more functions to the shower; all Hansgrohe valves and trims are compatible. So you can use the iBox to install a two-function shower using a diverter (built in to the trim, which may also feature a volume-control component). The diverter, as its name suggests, diverts the water to two (or more) shower heads.

Popular function combinations include overhead/body spray or shower head/tub spout or overhead/handheld (not shown):

two_function_overhead+handheld 2-function-tub-diverter

If you’d like, you can have more than two functions for a truly luxurious shower experience.



These require an additional three-way diverter rough to allow the water to flow to all heads and sprays. Some systems will need more roughs to allow multiple functions to be used simultaneously.

Many showers proudly wear (most of) their plumbing on the outside, going along with the popular exposed shower trend and allowing users to see how the water comes through the system:

Graff Exposed Thermostatic Shower System with Handshower
Graff Exposed Thermostatic Shower System with Handshower
Italbrass Bandini U Naos Collection Exposed Shower System
Italbrass Bandini U Naos Collection Exposed Shower System

So the next time your plumber hands you what you think is an exorbitant bill, remember the journey that your water makes before it comes through your shower head.


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