Many people (and I fall into this trap as well) refer to distilled water as if all distilled water was the same. It’s not. Yes, distilled water in general can be counted on to be quite pure, but there are many things that can cause differences in the quality of distilled water.
The Quality of the Distiller. Like any good manufacturer, we try to get samples of competitive distillers on the market. We operated them and dissect them. We want to stay aware of what’s going on in the industry. We are quite frankly shocked at the design of some distillers. The designers obviously have no idea how to make a good distiller, nor do they know some of the key features of a distiller. There are some distillers on the market that produce sub-par distilled water.
The quality of the storage container. A key element of a good distiller is the quality of the material that the distilled water comes in contact with. You have to be careful what you store high-purity water in, because water is a solvent. We store the fresh distilled water in high-quality glass or stainless steel. Some companies store the water in plastic. We’ve even seen a distiller that allowed distilled water to come into contact with copper and brass! Distilled water gets a bad name because most people’s experience with distilled water is buying bottled distilled water in low-grade plastic bottles (like milk jugs).
The freshness. To continue on with the point of the container, freshness matters! There is no way that distilled water stored in low-quality plastic containers will taste good, especially when you consider that it often sits in those bottles for months or even years!
Removal of gases. Another aspect of the distillation process is the removal of volatile gases (VOCs) and any substance that vaporizes at a lower boiling point than water. It sounds weird, but these gases can pass over in the distillation process and contaminate the distilled water, and yet the distilled water remains very pure. These VOCs can add a bad taste to the water though. We have a patented twin volatile vent holes that release these gases and we also incorporate a carbon post-filter, which is extremely effective at removing these gases. Lower end distillers don’t necessarily do this and bottled distilled water (if it’s for irons and not drinking) may still contain these gases.
Whether it boils dry. Finally, I have to mention a very common element of countertop distillers. The easiest and cheapest way to make a distiller is to allow the boiling tank to boil dry. When a heating element boils dry it super heats very quickly because it was the water that maintained the constant temperature. There are safety issues with this of course, but it also affects purity. The reason is simple, when the heating element is submerged in water the temperature cannot rise above 212ºF, which means that any chemical in the water that has a boiling point that is higher than 212ºF stays behind in the boiling tank. But as soon as the heating element boils dry and the temperature super-heats, it can vaporize those chemicals. Our water distillers are controlled by timer and are designed to never boil dry.