Mike Callahan
Licensed Plumber & Installation Expert
- Licensed Master Plumber (CA LIC #789234)
- 28 years residential plumbing experience
11
Articles published
H2O Insider
Publication
About
Mike has installed more water treatment systems than most people have reviewed. He contributes installation guidance, evaluates ease-of-install scores, and calls out any product that requires a professional where it claims DIY. He is based in Oakland, CA.
Testing & Editorial Standards
All H2O Insider reviews follow our editorial standards and testing methodology. Products are tested in real homes using Tap Score lab analysis. Affiliate relationships never influence our recommendations.