My understanding is that a whole house filter is typically a basic cotton filter to remove sediment mostly. If you want to filter out "carcinogens" (e.g. volatile hydrocarbons), then you're going to need a carbon filter.
We have a sediment filter in our system (water softener and two acid neutralizers required for the well water to be drinkable without bad taste). The filter is from "spun polypropylene" which looks like string wound into a filter cartridge.
The cartridge is 20 inches long, 4 or 5 inches diameter and we use a 50 micron filter. You can get the filters in finer and coarser sizes, but the acid neutralizers and softener take out a lot of the sediment before it reaches the filter. The finer the filter, the more pressure drop across it, however.
We replace the filter once a year, and I think a new filter runs around $ 40, but I don't write the checks out so I could well be wrong on pricing.
Before we installed the water treatment system and filter, fine sediment made its way through the water system and stained all the fixtures. In fact, over a few years there was about an inch of red clay mud built up in the bottom of the toilet tanks. After installing the neutralizers, softener and whole house sediment filters, the water is as clean as a typical city system.
I've contemplated a second filter with activated charcoal, but there's nothing in the well water here that requires further filtering according to the lab reports.
Our treatment system can be bypassed if necessary such as watering the lawn--there's a separate bypass valve on the filter as well. In fact, we don't use the bypass mode.
Jack