Is it one shower, every faucet or only the hot water? That is more useful information for a plumber than a guess about what needs replacing.
Weak flow can come from a fixture, the home's plumbing or the supply. Before discussing new pipes or a pressure regulator, find out where the change is happening and what has been measured.
Tell the shop when you noticed it, whether it was sudden and whether hot and cold water behave differently. Mention changes you've already noticed when other fixtures are used, but don't create extra tests to prove the problem.
If someone has taken a pressure reading, send it with the location and circumstances. A weak stream and a measured pressure are related information, but they aren't the same thing.
Also mention recent plumbing work and any earlier service reports. The plumber can use that history without assuming it caused the change.
For TMWA customers, its water quality information directs pressure questions to 775-834-8080, option 2. Describe the extent of the change and ask where to direct the concern.
If another utility supplies your home, contact that provider. A Reno mailing address doesn't identify the water supplier. If you use a private well, tell the company you call so it can confirm that it handles that system.
Water utility guidance describes plumbing side possibilities such as a restricted valve, a pressure regulator or a leak. Those are possibilities to investigate, not a reason to adjust equipment yourself.
If the plumber proposes replacing a regulator, ask what the measurements showed and why that work addresses the problem. If pipe replacement is recommended, ask which piping and what condition supports that recommendation.
The quote should say what gets repaired or replaced and how the result will be checked. A proposal to change one fixture and a proposal to replace piping throughout the house deserve different explanations.
For broader piping work, use the repair or repipe guide. It helps you see what each option includes before comparing the totals.