Flexible Water Supply Tubes and How to Use Them

In older installations, the water supply tubing running from shut-off valves to individual fixtures, such as faucets and toilets, was often made of chromed copper that was bent with special tools and fitted to fixture tailpieces and shut-off valves with compression fittings. But while these supply tubes are still used—especially when a nice appearance is wanted in exposed locations—more and more DIYers and plumbers are opting for convenient flexible supply tubes, many of which are available with the connection fittings already attached. 

  • NOTE: Flexible supply tubes should never be connected directly to a water supply pipe, but should connect to a fixture shut-off valve that is attached to the water supply pipe. 

Using flexible supply tubes is the best way to connect plumbing fixtures such faucets and toilets to the shut-off valves that supply them. Flex tubes are complete and ready to use with no flaring, cutting or bending required to install them. Using removable flex tubes makes it easy to change a faucet or toilet in the future because size adjustments are easily made. Flex tubes come with everything you need for installation, including screw-on nuts and washers on both ends of the tube. All you need to do is pick the material you want and the length needed for the project.

Before buying, it’s always a good idea to have a look under the sink or behind the fixture to see what length of flex tube you will need and the size of the end fittings required. There are many size and length combinations available, so it can get confusing. Often there is even a tag on the old flex tube that indicates the length and size of each end nut so you don’t have to measure or guess.

NOTE: Check local plumbing and building codes for any restrictions on water supply line materials. These restrictions are set at a local level, and while your community may comply with national code requirements, always check with your local practices, which will supersede any national code. 

Here are some of the flex lines you may find at the local hardware or home improvement store

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    Braided Nylon Flex Tubes

    Toilet water supply
    Aaron Stickley

    Flexible water supply tubes made from braided nylon come with a reinforced braided outer core and have a solid PVC inner core. They are usually white in color. This type of water supply tube is good for use with either hot or cold water supply lines. They can be used for most fixtures, including faucets, toilets and more. These flex tubes are very flexible,  so they can be bought long and easily looped if necessary. They come in a variety of lengths, and the attachment nuts may even have winged levers allowing you to hand-tighten the nuts without even the need for a wrench or pliers. 

    TIP: Hot water creates more wear on plastic supply lines, so it's a good idea to periodically inspect those tubes running supplying hot water faucets. These are more likely to fail than cold water supply tubes. 

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    Stainless Steel Braided Flex Tubes

    These flex tubes are made of braided stainless steel on the outside and usually a PVC inner core. The finish is a shiny metal with a textured, fabric-like look. The stainless steel on the outside is great in exposed areas, not only for the looks but also because the stainless steel protects it from the environment by resisting any corrosion. This type of supply tube is flexible but not quite as flexible as the braided nylon, PVC, or polymer-coated tubes. Stainless steel braided flex tubes are appropriate for either hot or cold water lines. Braided stainless steel is usually the most expensive option for flexible supply tubes, but is also the most attractive and most durable. 

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    PVC Flex Tubes

    Strong and durable, PVC flex tubes are made of a PVC outer core that is usually braided with nylon, and an inner core made of solid PVC. They are very similar to the braided nylon flex lines. This type of flex tube is often the least expensive option.  But although they are cheap, they are very flexible, offering amazing strength and ease of use. Keep in mind that PVC flex lines are not as corrosion-resistant when used in an exposed area—sunlight can weaken the material.  Of course, these are also hot- and cold-ready, and they are a great, inexpensive option for faucet and toilet connections alike.

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    Polymer-Coated Flex Tubes

    These flex tubes also have a PVC inner core but the outer material is made of polymer-coated fibers. Polymer-coated flex tubes look a lot like stainless steel braided lines, and like the stainless steel lines, they resist corrosion very effectively. Also, like braided steel, they are a good option where a premium appearance is needed, such as the exposed locations under a toilet or pedestal sink. Unlike the stainless steel version, though, polymer-coated tubes are very easy to bend and loop in situations where they are overly long, or when you need to make up for a big offset. Another difference is that this type of flex tube is very competitively priced. Like all the other flex lines, these are hot and cold water compatible, so they can be used for many applications.

Flexible Water Supply Tubes

Flexible water supply tubes are the easiest, most effective way to connect faucets, toilets and other fixtures to the water supply valves attached to supply pipes. This article discusses the four most common types of flexible supply tubes and how to use them.