Tap water tastes of whatever is dissolved in it, so the fix depends entirely on which taste you have. Chlorine, rotten egg, metallic, earthy and salty are five different causes with five different answers, and identifying yours first saves you buying equipment that was never going to help.
Name the taste before you buy anything
A swimming pool smell is chlorine or chloramine from disinfection. A rotten egg smell that is worse on the hot side is usually hydrogen sulfide, often produced in the water heater. A metallic taste points to iron, copper or corroding plumbing. An earthy or musty taste in summer is commonly algae related compounds from a surface water source, which are harmless but very noticeable. A salty taste suggests dissolved solids, sometimes from road salt or an over regenerating softener. Each of those goes somewhere different.
Free things that work first
Chlorine is volatile, so a jug of tap water covered and left in the refrigerator loses much of the smell overnight, and cold water tastes better anyway because the aroma compounds are less volatile. If the taste is only on the first draw of the morning, run the tap until it goes cold before filling a glass, because you are tasting water that sat in the pipes. If only the hot side smells, the water heater is the suspect rather than the supply. None of this costs anything and it narrows the problem quickly.
Carbon filtration, the workhorse fix
Activated carbon is what removes taste and odor compounds, and it is the active ingredient in pitcher filters, faucet mounts, countertop units and under sink systems alike. For chlorine and for earthy compounds, standard activated carbon is effective. For chloramine, which many utilities now use because it is more stable in the distribution system, catalytic carbon does a much better job and ordinary carbon can disappoint. Ask your utility which disinfectant they use before you choose, because the answer decides the cartridge.
Find out what is in it officially
If you are on a community water system, the utility publishes an annual Consumer Confidence Report and the EPA maintains a finder for it. That report tells you the disinfectant, the source and what was detected, which turns a guess about your taste problem into a known cause. Well owners have no such report and need a lab test instead. Our guide to what state has the best tap water covers how much these supplies genuinely vary across the country.
When the taste is a warning rather than a nuisance
Most taste complaints are aesthetic. A few are not. A sudden change in taste, smell or color that was not there last month is worth investigating rather than filtering, especially on a well or after work on the mains. Salty or metallic tastes that appear abruptly, or any taste change accompanied by a boil notice, mean you stop and find out the cause first. A filter that masks a change hides information you wanted.
Questions people ask about how to make tap water taste better
Does boiling water improve the taste?
It drives off some chlorine, but it also concentrates minerals as steam leaves and makes the water taste flat. Chilling in the refrigerator gives a better result for taste and costs nothing to run.
Do pitcher filters really work?
For chlorine taste and odor they work well, which is what most people are buying them for. They do far less against dissolved minerals, nitrate or hardness, and their cartridges have a short life.
Why does my water taste worse in summer?
Surface water sources develop seasonal algae blooms that release earthy and musty compounds, and warmer water carries the smell more strongly. Carbon filtration handles it and the taste usually fades with the season.
Will adding lemon or a filter jug fix a sulfur smell?
No. A rotten egg smell is hydrogen sulfide and it needs the source found, commonly the water heater anode rod or a well problem. Masking it does nothing about what is producing the gas.