You've probably been there — ready to enjoy a nice, relaxing shower only to look down and realize there are three knobs. If you've got zero understanding of how this configuration works, you're not alone.
Maybe you're in a hotel with an unfamiliar three-knobbed shower, or perhaps you're visiting a friend who forgot to leave instructions on how to enjoy that refreshing rinse. No matter your circumstances, understanding the role of each of the three knobs can help you not only turn on the shower but also make sure it's just the right temperature for you.
Knobs for Basic Shower Usage
Shower systems have a variety of different valve and knob configurations. These usually depend on the plumbing in the building, building codes or the way the shower was originally built. Some have a single knob, which you can swing to adjust the temperature from cold to hot. This type of knob usually opens both of those water lines and adjusts the temperature according to how far the user has turned the handle before the water is released from the spigot.
Other showers have two knobs, one that controls the hot water and one that controls the cold. You can play around with either for your desired mix of hot and cold water from the main faucet or showerhead, adding a little hot or cold water when you desire.
Diverter Valve Placement
When a shower has a third knob, it's probably a diverter valve. As the name suggests, this is the valve responsible for diverting the water and adjusting shower flow to the place you need it to go. In showers with just one or two knobs, this diverter is typically a small handle or lever on the water spigot. You might pull it up to get the water to flow out of the showerhead or push it in to keep water flowing out of the faucet to fill up a bathtub.
In showers with three knobs, the diverter valve is not a small part of the shower spigot. Instead, it's the third physical knob that often sits between the hot and cold knobs. Usually, the cold knob is the one that sits toward the right, but that's not always the case.
Sometimes, the third knob has the same outer fixture and appearance as the temperature knobs. Other times, it looks more like a handle or a switch. In any case, it performs the job of adjusting the flow of the water.
Using Three Knobs
Once you understand the purpose of each knob, it's easy to figure out how to use a shower with three knobs. First, use the temperature knobs to adjust the water to your liking. Each shower and internal pipe system is different, and some knobs can be very temperamental, but you can do this by slowly adjusting both the hot and cold knobs until the temperature is just right.
Then, turn the third knob in the direction that directs the flow to where you want it to go, whether that's to the showerhead to take a shower or to the faucet to fill up the bathtub. When you've finished your shower or filled the tub enough, you can turn both temperature knobs to their off positions to stop the flow of the water, and then return the third knob to the position in which you found it for the next user.
Rachelle Dragani is a freelance writer based in Brooklyn with extensive experience covering the lifestyle space. Her work on topics including smart home technology, pest control, living green, budget home repair and helpful household tips have appeared in publications including Bob Vila, Esquire, Popular Mechanics, Gizmodo and Yahoo.