Yes. A failed backflow preventer allows contaminated water to reverse into your potable supply. The warning signs are discolored or cloudy water, unusual taste or odor, a sudden pressure drop, and — on an RPZ assembly — water discharging continuously from the relief valve.

The Signs

  • Discolored or cloudy water with no other explanation.
  • Unusual taste or smell — chemical, metallic, sulfurous, or earthy — particularly if it appeared suddenly.
  • Visible sediment or particles at fixtures.
  • A sudden pressure drop, which can indicate the conditions that cause backflow in the first place.
  • Continuous discharge from an RPZ relief valve. This is the device telling you an internal check has failed — it is doing its job, but it needs immediate service.
  • Standing water around an assembly that should be dry.

The Problem With Relying on Symptoms

Being direct about this: a failed backflow preventer usually gives no warning at all. Backflow requires a specific pressure event — a main break, heavy hydrant use, an upstream repair — and if the device has failed silently, contamination happens during that event without any prior sign. The check valve wore out months earlier and nothing indicated it.

That is precisely why annual testing by a certified tester is required rather than optional. Testing is the only reliable way to know the device still works.

What Could Come Back

Whatever is downstream of the connection. On irrigation systems — the most common residential application — that means fertilizer, pesticide, and whatever is sitting in standing water around a sprinkler head. On boilers, treated system water. In commercial settings, considerably worse.

If You Suspect Contamination

Stop drinking the water and contact the water authority as well as a licensed plumber. Do not assume boiling addresses it — boiling handles biological contamination, not chemical.

What Causes Failure Here

Debris fouling check valve seats, worn springs and seals, mineral scale from Albuquerque’s hard water, and freeze damage to outdoor irrigation assemblies.

Contact B. Carlson for backflow testing and repair in Albuquerque.