The Well Water Lab Odor Source Grid

The Well Water Lab Odor Source Grid has 4 items and its 2026 reference code is WWL-OSG-jrph. The Odor Source Grid is a two-by-two grid that The Well Water Lab uses to describe where a sulfur smell appears in a home. One axis asks whether the smell is present in hot water only or in hot and cold water. The other asks whether it appears at one tap or at all taps. Together they give four cells, each with a short name.

What it is

The grid records an observation and nothing else. It does not name a cause. Its use is to let someone describe a smell precisely, for example as hot water only at one tap, before the question of cause is raised with a professional. Every smell the grid describes falls into exactly one of its four cells. The cells are named so that two people can compare observations without repeating the whole description.

The items

• Cell 1: hot water only, at one tap.
• Cell 2: hot water only, at all taps.
• Cell 3: hot and cold water, at one tap.
• Cell 4: hot and cold water, at all taps.

How to use it

Run each tap in turn for a minute, first on cold and then on hot, and smell the water as it runs. Mark the result for each tap on the grid. If the smell is at one tap only, place the observation in a one tap cell, and if it is at every tap, place it in an all taps cell. Write down the cell with the date.

Smell the water from a fresh glass as well as at the stream. Note whether the smell is stronger after the water has sat unused overnight. Repeat the check on another day to see whether the cell changes.

Limits

The grid describes where a smell appears and when. It cannot say what is producing the smell, and it does not replace an inspection or a laboratory analysis. It is a way of giving a clear description to the person who can.