A portable digital device for testing water meters is a portable device designed to measure the accuracy and quality control of domestic water meters up to a size of 1 inch in place and without having to open the tested meter. This machine is designed in accordance with the International Standard ISO 4064-3 and meets all the basic requirements for controlling the accuracy of the measured meter under test. This device is based on a comparison of the volume of water read by the water meter tested with a precise volume measurement reference in the specified discharge (nominal flow, minimum discharge, and maximum flow rate of the meter tested). The portable digital device for testing water meters is able to pass through the volume of water and instantly read water at a very high precision and digitally. There is always a need for such a system to control the accuracy and accuracy of the water meters installed on the site by subscribers from the water and wastewater organizations that are suppliers and distributors of refined and sanitary water supply in different cities. Because the inaccuracy of water meters performance can impose heavy and heavy losses on water and wastewater organizations or their subscribers in the long run and ultimately lead to a lack of return on investment by water and wastewater organizations or customer discontent. Subscribers' objection to the cost of water consumed is a problem that all water and wastewater organizations face. In these cases, most subscribers consider the increased cost of water consumed as inaccurate and accurate to their water meter performance, and are keen to test the accuracy of their water meter in their presence. On the other hand, reducing or increasing the unconventional consumption of a subscriber can increase the likelihood of leakage in the user's plumbing system, the failure or non-accuracy of the meter or manipulate it for water and wastewater organizations, which is also measured by accuracy The meter can be tracked at the installation site.