Rain catchment is a good way to top-up your tanks. Some sailors set up tarps to catch and lead the water into Jerrycans, others have the water flow directly into their main tank — we don't recommend doing that unless you've got a good filtration system. When it rains, we collect water trickling down from our aft solar panel, or from our inverted cockpit tent (see below picture, see pictures of our boom tent), into bowls or directly into Jerry cans. We collected this extra water for showers, laundry and washing dishes.

bowls set under an inverted cockpit tent to catch rain water

While the rain itself might be safe to drink, it carries dirt or whatever may be on your tarp, or deck. And depending on where you are, the rain may have environmental pollutants mixed in. For these reasons, I recommend using rainwater for purposes other than drinking and cooking. If you are to drink it, it's important to boil it first for at least 1 minute, or to run it through a good filter. See water filtration.

Even if you don't plan on drinking it, it's a good idea to treat the water you catch. Before treating, make sure to filter debris out of the water.

Filtering debris. If you don't have a good filter to remove debris/impurities, run the water through a coffee filter. We like to put a funnel over a large container, and to line it with a coffee filter. The filter will eventually get saturated (especially if the water is dirty), and the flow of water will slow down, it may be necessary to replace the filter.

Adding bleach to water. Adding bleach is a reliable water treatment method. This is something we've done, and continue to do. The suggested ratio of chlorine to water is 2 drops bleach for 1.14 liters (1 quart). Use a dropper for more precision. The above ratios are for bleach containing 5.25% Sodium Hypochlorite. This amount depends on the concentration, the ratios will be different for 5.25% than for 8% chlorine bleach (1 drop: 1.14 l). Only use regular, unscented chlorine bleach products that are suitable for disinfection and sanitization, as indicated on the label. Allow the treated water to stand for 30 minutes. A good way to remember these ratios, is this saying:

“You must be 21 to drink”.

Things to remember: