Repairing or replacing the underground cold feed into the house from the street:
If you do begin to notice water lying where it should not be. Than make sure all taps are off inside the house and taking a large screwdriver remove the cover over the street mains cold supply and placing the screwdriver tip on the tap top place your ear on the top of the screwdriver and listen for the sound of hissing water coming out of a burst under the ground between this tap and the underneath of the house. If you do hear a hiss shut the tap off overnight and check to see if the water level stops rising on the ground outside the house. Also check under the house for any leaks with a torch if possible.
Once these tests show you do indeed have a leak you have two choices. Either dig up around the leak and locate this very burst or bite the bullet and simply replace this cold feed line in with a new alkathene line.
It really depends on what you have under the ground now. If the pipe is rusted out in parts then it is best to replace the entire length from the street shut off to the underside of the house.
The new piping for this task comes in long coils. And you will need to use a ¾-inch (20 mm) diameter to ensure a good supply unless the pressure is quite low now in which case it will be wiser to run 1-inch (25 mm) diameter piping in. Or simply half-inch (15 mm) if it is very good high pressure.
You dig your trench spade depth under the lawn and deeper in the garden if others will be digging near it. You can dig around the outlet of your street shut off valve and gain access to the pipe work under the ground now. You will have to hacksaw or sabre saw this pipe out of the way if made of galv steel. And with a wrench on the outlet side of the tap screw out the old section of pipe.
Wind in the alkathene adaptor fitting a couple of turns and then wind on the plumbers plastic tape (PTFE) quite a few turns and then tighten with a pair of plumbers’ pump pliers. Then remove the big nut and the flared tapered ring collar and place on the end of the pipe and place lubricant on the O-ring left inside the main body and extra collar. Then push the pipe home past the O-ring and bring up the flared collar and start the nut off and tighten to complete this first joint.
Then roll out the coil piece by piece into your trench. If you have tunneled under a pathway you will need to uncoil the pipe and twist out the loops and feed it under the path with some sticky tape on its end. And then carry on feeding it into your trench until you reach the entry joint under the house or near the house. Where you will repeat the fitting of another alkathene adaptor fitting. Sometimes you may have to bridge the end of the alkathene through with some poly pipe in under the house. Test and fill in your trench being careful not to place any sharp stones up against the new pipe under the ground. Replace the ground covering same out on the street.