Desert sun, UV and your tote

What UV does to a bottle

Polyethylene breaks down under ultraviolet light. The surface goes dull and chalky, the colour yellows, and the wall becomes brittle. A chalky bottle may look sound and still crack the first time it is bumped or filled. That is why the grader treats a chalky bottle as a rebottling candidate and not as a used one.

Heat makes it worse. A tote on black asphalt in Indio in July is baked from above and below. The same tote under a roof in Ontario will last much longer. There is no number that applies to every case, so read the surface and not the calendar.

Covers, shade and ground

An opaque cover stops UV and stops algae, which need light to grow. A tarp works, as does a purpose-made tote cover, a shade structure or a position in the shadow of a building. Keep the tote off bare dark pavement where you can, and keep the cover from trapping heat against the plastic.

For a rain tote, a cover must still let water in. Use a screened inlet and keep the rest dark. See catching rain in a tote.

Water in the sun

Warm water holds less oxygen and grows algae faster. A tote of irrigation water in full desert sun will go green within weeks if the bottle is clear. A covered tote stays cooler and cleaner. If you must leave it in the sun, expect to drain and wash it more often.

Texas A&M AgriLife notes that a 1,000-pound heifer may need about 20 gallons of water a day in hot weather. That is a reminder that heat raises demand as well as damaging the plastic, and that animal drinking water needs a tote with clean, documented history. The food-grade page covers that.

One more thing to try

Hold a white card behind the bottle in daylight. If the plastic looks yellower than the card, it has aged. Compare with the inside of the lid, which is usually shielded and shows the original color.

Questions people ask