Flint water crisis - Water filter for Hot water heater?
There are many systems on the market that could make the tap water safe to drink, but there is no one size fits all solution. These systems also range into the tens of thousands of dollars. You would need to get your water tested by an independent lab to determine what the quality is, and then you would need to have a system designed that will fit your needs. In your situation, you would need a system that has multiple stages in it.

Here is a list of components that would most likely be needed. If you are working with a professional, you may find that some of these are optional. There are also other types of filters on the market which are not listed that could work instead.

This list is respective to the flow of water that is coming from the city.

Whole house sediment pre-filter - This will remove the largest particles out of the water such as sand, rust deposits, etc.

Whole house sediment filter - This filter captures smaller particles than the pre-filter. They go down to at least 5 micron.

Whole house carbon filter - These filters can remove some harmful chemicals that are in the water, but do little, if anything for lead.

Whole house UV filter - This filter will kill off most bacteria and viruses. It has to be installed after the other filters because small particles can block the UV rays, and bacteria and viruses could survive it.

Water softener - This will remove some of the minerals that cause hard water stains.

Reverse osmosis system - This would be the final stage of filtration. These systems can be located under a sink, and filters out virtually everything except pure water. These systems do not produce very much water, and use a pressure storage tank because it takes a while to produce enough water.

The other systems before the reverse osmosis system condition the water in the building well enough to be used for most purposes except for drinking. Under normal circumstances, the water will be safe to bathe in, and do laundry with.

Please note that the addition of these filtration systems could reduce your water pressure significantly. You may need to install a pressure boosting pump and storage tank as well, if there are pressure issues.

However, these steps should all be done by the municipality. It should not be the burden of the homeowner to render the tap water safe to use.