Materials matter. So does design. Plastic strainers are inexpensive, but they, or their bowls, are vulnerable to chemicals in some anti-freeze concoctions (see PS December 2017 ”Winterizing Wisdom from the Chemistry Lab”).

Some designs are clearly easier to inspect and clean. Given the propensity for weeds and algae to get sucked into our boat’s cooling system, ease of maintenance is high on our list of desirable features.

1. Testers found the square openings on the Vetus filter are more difficult to clean than other kinds of perforations.
2. This close up shows a perforated strainer basket typical of popular intake filters.
3. This inexpensive Sureflow filter has a wire basket. It’s nylon bowl is vulnerable to some antifreeze.
4. Groco’s poly propylene filter features square holes like the Vetus.
5. The Perko silicon bronze housing with glass bowl and perforated metal strainer has been around for decades.
6. The water-activated activated bilge switches we tested in September 2005 had small strainers to protect against debris.
7. Two levels of grating protect the automatic float-switches from clogging. Although these are not commonly vulnerable to clogging, a plastic bag or large debris could interfere with it. A DIY strum box would add another layer of protection.