One of the best professional cleaning solutions that won’t leave streaks is one gallon of distilled or bottled water mixed with 2 to 4 teaspoons of dish soap. Apply using a sponge in a figure-eight motion, and then use a squeegee to remove the majority of the water and soap. You can finish drying with a piece of old black-and-white newspaper to remove any residue for a streak-free clean every time.

Hard water stains can permanently damage your glass if left untreated. The minerals dissolved in the water can etch the glass, causing long-term damage and affecting the overall integrity of the surface. Luckily, it is pretty simple to remove hard water stains by using vinegar, baking soda, or commercial cleaners.

Window cleaning costs around $220, on average, but you could pay anywhere from $150 to $300 or more, depending on the number of windows, how accessible they are, and the type of windows. Some professional window cleaners charge on a per-window basis at around $10 per window, while others provide a single price for your entire home. Either way, more windows will mean higher cleaning costs. Picture windows tend to be the most affordable because they don’t require cleaning of internal components, while double-hung windows and skylights increase your price because they’re more complicated to clean and less accessible.

A professional cleaning service generally takes a few hours, typically between 2 to 4 hours, depending on the property's size and the severity of any stains. Keep in mind that wet cleaning methods will require additional drying time.