NO! Rainwater is considered superior to tap water because it is rich in oxygen and lacks the salts that can build up in soil. Farmers y do not boil irrigation water due to the high cost and impracticality . They  filter water to remove sand, debris and algae, which clog equipment.

Rainwater is generally not harmful to plants; in fact, it is considered the best water source because it is naturally soft, free of chlorine and fluoride, and slightly acidic, which helps plants absorb nutrients. It acts as a mild fertilizer due to natural nitrogen absorbed from the air.

Potential Concerns and Tips:

• Contaminants from Roofs: If collecting rain from a roof, be aware of debris, bird droppings, or asphalt shingle residue. Using a first-flush diverter can minimize this.
• Acid Rain: In highly industrial areas, rain can be excessively acidic, but this is rarely a major issue for most gardens.