Why Does My Water Smell Like Sulfur or Rotten Eggs After a New Install?

A short diagnostic tells you which one you are dealing with, so you do not replace the wrong thing. Start with the three quick checks below. If the smell is in the cold water, is still present in a glass carried to another room, and does not clear after a thorough flush, then it is a water-source issue (common on well water) and should be sized for treatment.

Run These Three Checks First

• Cold versus hot. If only the hot water smells, the source is very likely the water heater (its anode rod reacting with the water), not your filter.
• Water versus the room. Fill a glass, walk it to another room, and smell it there. If the glass smells fine away from the sink, the odor is coming from the drain or the sink area, not the water.
• How long you flushed. A brand-new system can carry a brief break-in odor that clears with a proper flush. If you have not flushed thoroughly yet, do that first.

Safety Before You Start

• Do not drink water that has a strong sewage-like or septic smell, and stop using it for drinking until the source is identified. A rotten-egg smell from sulfur is usually a nuisance odor, but a sewage or septic smell can indicate contamination.
• If anyone has symptoms of illness alongside the water change, stop using the water for drinking and contact support and, if needed, your local health authority.
• Before any work on the system, shut off the feed water and relieve pressure at a nearby faucet or the system valve.

The Full Diagnostic, Step by Step

1. Flush first. If the system is newly installed and you have not done a full flush, flush per the system instructions. A short-lived break-in odor on a new system is normal and clears with flushing (see the startup and flushing KB article).
2. Compare cold versus hot. Smell the cold water and the hot water separately. A smell on the hot side only points to the water heater, commonly the anode rod, and is handled by a plumber or the heater manufacturer, not by your filter.
3. Do the glass-in-another-room test. Fill a glass at the affected tap, carry it to a different room, and smell it there. If it no longer smells, the odor is from the drain or the sink area (often bacteria or biofilm in the drain), and the fix is cleaning the drain, not changing the filter.
4. Check whether it is well water. Well and some surface sources can carry hydrogen sulfide. If the smell is in the cold water, persists in the glass test, and survives a thorough flush, treat it as a water-source odor.
5. If it is a water-source odor, get the right treatment sized. Hydrogen sulfide removal depends on how much is present and your water chemistry. Contact support with your water details so the correct treatment can be recommended; do not assume a standard cartridge alone will fully remove it.

Quick Summary

• If only the hot water smells, the source is very likely the water heater (its anode rod), not your filter
• If a glass of water smells fine carried to another room, the odor is coming from the drain or the sink area
• A brand-new system can carry a brief break-in odor that clears with a proper flush
• A smell that stays in the cold water, survives the glass test, and outlasts a thorough flush is a water-source odor (common on well water) and should be sized for treatment
• Do not drink water with a strong sewage-like or septic smell until the source is identified

Need Help Finding the Source?

Our support team can run the diagnostic with you and size the right treatment. Reach out to Crystal Quest support if:

• The smell is in the cold water, survives the glass-in-another-room test, and does not clear after a thorough flush. This is a water-source odor that should be sized for treatment.
• You have well water and want the correct hydrogen-sulfide treatment recommended for your chemistry.
• You are unsure which source the diagnostic points to.