Prepare the Job
In order to install a water meter properly, you will need to flush the water lines upstream of the meter. Doing so will remove any buildup in the water lines and will protect your new meter as it is installed. You might need to remove spud protectors from the meter. Place it into the line, with the meter face easily viewable for inspection. Most are installed horizontally with the face pointing upward. The arrows on the body of the device will indicate the direction in which the water should flow. Some meters will be required to have a bypass line installed as well, although this varies depending on locality.
Make the Connections
Tighten the connections on the water meter sufficiently to keep it in place, but do not overtighten them. Sealant or Teflon tape will keep them sealed without the need to torque them too hard. Connect the wires on the reed switch to the wires of corresponding color on the meter unit. This must be insulated properly so that water and weather do not cause damage over time and necessitate a replacement. Make sure that the unit is in place and ready for use before you turn the water flow back on.
Turn on the Water
At this point, you should be able to turn the water back on to the meter. Slowly open the upstream valves that were turned off prior to installation. Turning these on too quickly will flow into the unit too quickly and cause damage to the meter. Make certain that the water is flowing through the unit. You might want to do a leak check on the meter to ensure that it is properly sealed. Once you have checked for leaks, open all valves; your unit is now ready for use.