Taste - At the moment, there is no definitive water test for taste.  Taste is extremely subjective and changes from person to person.  If you have a persistent taste in your water, it is probably traceable to one or more of the following:

Chlorine - Your water company may have increased the dosage of chlorine to counteract a possible bacterial issue. A charcoal filter will help remove the chlorine taste.

Algae - The reservoir water source may be experiencing a blue-green algae bloom.  This usually happens in the warmer part of the summer.  Occasionally, underground piping develops an algae growth and will need to be flushed out to correct the problem.  Sometimes a charcoal filter will help remove some of the offensive taste.

Iron - You will notice reddish-brown staining in your shower and sinks.  A water softener will usually remove the iron in the water. The problem may be with iron and sulfur bacteria

Hydrogen Sulfide - This problem is accompanied by a rotten-egg smell.  Your nose is sensitive to 1 part per billion sulfide, so it doesn't take much to be offensive.  Remediation of this problem will require professional advice from a water treatment company. See iron and sulfur bacteria

New Water Source - During peak demand periods, your water company may employ a new water source that may change the taste of your water.  The difference will disappear as soon as demand allows the additional source to be shut off.