The answer is Field Water Alarm® by Jacobson Remotics LLC Now you can stop watching water and start saving time. Regardless of fluctuating head pressure, soil moisture content, or grass density, you know exactly where to close your pots or change to the next set or pass the water to the next user saving you time and water while reducing runoff.
These units are durable, watertight, portable, user friendly and easy to set up. Both the cell phone and radio units are powered by a sealed 12 volt 7 AMP rechargeable lead acid battery. All of them come with a 12 Volt 7 -800mA battery charger (see image below)
Each battery is wired with a plug that prevents reversing the charger polarity or the controller module. If you would like hand-held 2-way radio receivers, they may be ordered separately. Radios are frequency specific and can be matched to your requirements. A SIM card for the modem can be purchased from AT&T or T-Mobile. Signal cords work well up to 100 feet and are also available.