Some considerations when choosing filtration for rainwater.
1. What will you be filtering for?
That is, what might be in the water that you want to remove... With Rainwater, that's mostly going to be whatever comes from your roof/catchment surface.
- What is your roof made of? Is it flat or sloped? Is there any vegetation hanging over your roof?
- Will you also be using well or hauled water in the system?
- Testing your rainwater is a good idea.
2. How much flow you need (gallons per minute - gpm)
Various filters limit flow, and you want to be sure to have enough flow to meet your household's needs.
- Small home/RV (1-2 occupants): 4-6 GPM
- Small-Medium home (2-4 occupants): 7-8 GPM
- Medium-Larger home (4-6 occupants): 10-12 GPM
- Large home, small restaurant, duplex, etc. (6+ occupants or frequent guests): 16+ GPM
3. Maintenance
- A UV bulb needs to be replaced annually, and the quartz sleeve needs to be cleaned regularly. Changing a delicate UV bulb can be a precarious process, and the quartz lamp sleeves are fragile and vulnerable to fractures. There are a few product options with "quick connect" bulbs (more expensive, easier to maintain). Cactus Rain also offers an alternative disinfection product - the Clairify - that does not require any maintenance.
- Other filters - sediment, carbon, specialty - typically need to be changed annually.
4. Availability of filters
- 20" are standard and therefore there are more available filters in the market than for a smaller system.
5. Inlet/outlet size to match your plumbing
- An RV might have 3/4", while a household supply will more likely require 1"-1.5".
- Also consider Normal Open/Normal Closed defaults
6. Wasted water
- Your rainwater is precious, don't waste any of it! Avoid systems with backwash or brine discharge like RO. Some UV systems also have a backwash for water that gets over-heated when not flowing.
7. Monitor for Leaks + Automatic Shutoff
- We strongly recommend a smart water monitor with automatic shutoff for rainwater systems. Losing your stored rainwater in the event of a leak could be catastrophic!
Q&A: What about just using a pitcher filter for drinking water?
Plumbing code requires filtration and disinfection that meets NSF 53 for rainwater catchment systems to provide potable water to your house. You may not be able to get a building/plumbing permit, or you might have trouble selling your house if the water supply does not meet code.