10ft is quite long but it will depend on the temperature and pressure of the keg, also slightly on the tap you are using, there are calculators online which tell you the length of 3/16" needed. I started with about 3m which poured without foam but was painfully slow. I removed roughly 10cm, tried again, removed another 10cm and kept going until I had a good balance between foam and pour speed - this is called balancing the lines. 3/16" pipe is cheap, I ordered 20m which was enough for my 4 taps and some additional for if I need to replace any. I could also make a longer coil if I brew a beer which should be highly carbonated.