Common toilet supply line sizes vary by region so always confirm before you buy.

For toilets the most common configuration you will encounter is a compression nut at the shutoff valve and a tapered or nut end at the toilet fill valve. In many Canadian homes the valve end is typically three eighths inch compression while the toilet fill valve takes a seven eighths inch threaded shank with a nut, so you buy a hose that matches those two ends or use an adapter. In parts of the United States, and particularly in some Florida installations, the shutoff valve often uses one half inch compression which will not fit a three eighths inch connection without an adapter or a different hose. Measure the outside diameter of the valve threads and the threaded shank on the fill valve rather than relying on what you think was installed because older hardware and regional variations can look similar but differ in size. If you are replacing a line bring the old one to the store or use a caliper to get accurate measurements, and carry a small thread pitch gauge if you can to distinguish fine from coarse threads. When installing, tighten compression nuts until snug and then add a quarter turn to seal; do not overtighten because that will damage female fittings and cause leaks.

Common mistakes are assuming all toilets use the same size and buying a universal replacement that does not match the valve end, which you avoid by measuring the valve and shank or bringing the old hose to the store. Another error is overtightening or relying solely on plumber tape on compression fittings, which will cause leaks or cracked fittings; hand tighten and use a wrench for an extra quarter turn and never apply tape to compression seating surfaces. A third issue is ignoring adapter compatibility and thread type differences, such as mixing a tapered pipe thread with a compression fitting, so choose the correct adapter or replace the shutoff valve with a compatible one if the mismatch cannot be resolved.

BigHomeProjects.com helps homeowners find local contractors who can confirm valve sizes, recommend properly matched supply lines, or replace valves if needed. We also help contractors find work and participate in our discussion community where members share measurements, photos, and practical installation tips.

Recommended Links:

Contractor Directory Website: https://www.bighomeprojects.com/
List your Business with Us: https://bighomeprojects.com/add-listing/contractors/
Subscribe to our Newsletter: https://acumbamail.com/newform/web/YhV8H72kPdyzMrrdh8xtbtvyqRotvSPfUCXaRM8cf/53636/