Do you really need a dehumidifier? Well that depends on a number of things.
How air-tight is your home? Newer homes are often sealed better and can trap moisture & humidity more so than older homes. Does your home have any leaks from plumbing or where water gets in. How many occupants are in the home that are showering, cooking and doing laundry.
The best way to know if your humidity is too high is to is to measure what the relative humidity (Rh) levels are in your home. You can buy a hygrometer to accomplish this from you local hardware store and . Canada Housing and Mortgage Corporation (CMHC) recommends indoor RH at 30% to 45%, to a maximum of 50%. In summer, this can be a trick in a basement without the use of a dehumidifier.
Generally May is the time of year we should start to use a dehumidifier in our basement to reduce humidity levels. They work best in the warmer months up until about November. While central air conditioning removes humidity as well it doesn’t run continuously and is not triggered to work in the presence of humidity like a dehumidifier does to help to control indoor moisture. Newly built homes have considerable moisture and will likely benefit from running a dehumidifier regardless of the time of year. Of course, removing the source of moisture (e.g. from a leak) should be a priority.