The lifespan of a 7 inch wet tile saw blade can vary widely based on several factors, including:

1. Material Being Cut: Cutting harder materials like porcelain or granite can wear out the blade faster than softer tiles.

2. Frequency of Use: Regular use will naturally reduce the blade's lifespan compared to occasional use.

3. Blade Quality: Higher-quality blades with better construction and materials tend to last longer.

4. Cutting Technique: Proper technique and maintaining the correct speed can prolong the blade's life.

On average, a good-quality wet tile saw blade can last anywhere from 15 to 50 hours of cutting time. Regular maintenance, such as keeping the blade clean and ensuring proper water flow, can also help extend its lifespan.