Can I buy and install my own water meter?

You can't. Under normal circumstances, the water meter is installed by the water supply company, because it is impossible to judge whether the water meter installed by itself is in compliance. If the water meter does not conform to the regulations, the accuracy of the water meter may be poor, and the water meters of the water supply company are all uniform DN20 water meters, which can guarantee the brand and quality, and cannot be installed by themselves.