The Well Water Lab Filter Stack Order

The Filter Stack Order is the sequence The Well Water Lab uses to describe a whole-house water treatment train. It lists five stages, in order, from the point where water enters the house to the taps. Describing the stages in a fixed order makes it easier to compare one setup with another and to see where a particular piece of equipment sits.

What it is

A treatment train is a set of devices installed in line, each doing one job. The order matters because equipment placed early protects the equipment that follows it. The Filter Stack Order is a description of that order, not a recommendation to install every stage. Many homes use only some of the five.

The items

• Stage 1, sediment: a filter that removes particles before they reach later equipment.
• Stage 2, iron and manganese: treatment for dissolved iron and manganese.
• Stage 3, softening: an ion exchange softener for hardness minerals.
• Stage 4, carbon: a carbon filter for taste and odor.
• Stage 5, ultraviolet: a final ultraviolet unit for disinfection.

How to use it

Draw the pipe from where water enters the house to the first tap and mark where each device sits. Number each device with the stage it belongs to. Gaps are expected, since few homes need all five stages. Compare your drawing with the order above and note any device that sits out of order.

Label each device with its brand and model so the drawing stays useful.

Limits

The order describes how the site talks about treatment. Which stages a well actually needs depends on a laboratory analysis of the water, and sizing and installation belong to a licensed professional. The order should not be read as a design.