Since water heaters actually use the plumbing system, you might expect that plumbers will actually deal with them just as they deal with the rest of your plumbing. However, the truth is that not all plumbers deal with these types of issues, as they might not specialize to handle water heater repair.
Depending on the kind of system you have, your water heater could be somewhat more complex. Also, if it uses natural gas for heating, then you might have to call in a certified expert who can deal with gas pipes safely. Otherwise it could lead to a serious safety hazard, if there is a gas leak.
In most cases, the actual plumbing part can be tackled by an experienced Denver plumber. They can check to see if there are any leaks and water pressure losses, and they can at least provide you with their expert opinion on what needs to be done. If you have to call in another expert as well, they will tell you, and they’ll make sure to do their part in the meantime.
Calling in a plumbing professional is usually a good idea in such cases. You can at least have them inspect the system and give you some insight to let you know what might be needed. Then you can make an informed decision going forward.