Old water heaters and Albuquerque's hard water
Albuquerque's water leaves scale, and over the years a tank holds on to it. That can make an old water heater harder to drain and heavier than the label suggests. Here are the utility's own numbers and what they mean when the tank has to go.
How hard is the water?
The Albuquerque Bernalillo County Water Utility Authority calls its water moderately hard to hard, depending on the blend of sources (ABCWUA). Its 2023 zone reports show a citywide range of about 2 to 12 grains per gallon, and a city average of a little over 8 (ABCWUA 2023). Zone averages ran from about 7.3 to 10. To convert parts per million to grains per gallon, divide by 17.1.
The utility also says bits in your hot water may be calcium carbonate scale from the heater, and that a high thermostat setting can make scaling worse (ABCWUA). If your faucets show white flecks, you are likely seeing some of it.
Why this matters when the tank comes out
- Scale settles at the bottom, right where the drain valve sits, so a slow or blocked valve is common on old tanks.
- A tank that will not drain still holds water, and water weighs about 8.3 pounds a gallon.
- Scale that stays in the tank stays in the weight.
We have no standard figure for how much scale an old tank holds, because it depends on age, water and how often it was flushed.
Draining an old tank
If you are replacing a heater, your plumber does this as part of the job. If you are doing it yourself:
- Have the gas, power and water handled first. A gas line needs a qualified technician (NMGC).
- Let the water cool. Tank water can scald.
- Connect a garden hose to the drain valve and run it to a floor drain or outside.
- Open a hot water tap in the house, or the relief valve, so air can get in.
- Open the drain valve and wait.
If the flow stops with water still inside, the valve is probably plugged with scale. Do not force the valve, because old brass and plastic valves can break off. Call your plumber.
Where an old tank can go
| Route | Terms |
|---|---|
| City large item pickup | Water heaters are on the list. Residential customers, at the curb (City) |
| City convenience center | These refuse waste with free liquids, so empty it first (City) |
| Los Lunas transfer station | Takes water heaters, emptied (Village of Los Lunas) |
| ReStore | Listed as drop-off only, gently used and resaleable (Habitat) |
While the old one is out
Ask your plumber about the new heater's thermostat setting and how often to flush it. Those two decisions set how much scale the next tank collects.
If you would rather not deal with it
Water Heater Removal covers this job, and quotes are free. Call (505) 657-3255, any day from 7 AM to 7 PM.
