ResMed H5i Standard Water Tub

Quick answer: This is the genuine ResMed standard water tub for the H5i heated humidifier (part 36803), used with the S9 series. It’s the reservoir that holds the water your humidifier heats to add moisture to your airflow. The standard tub is a sealed, disposable component designed for straightforward periodic replacement — if you’d prefer a chamber that opens for thorough cleaning and reuse, ResMed also makes the cleanable tub (36800).

What’s included

• 1 × ResMed H5i standard water tub (part 36803)

Humidifier and device not included.

About this part

The H5i heated humidifier warms water in the tub so the air delivered through your tubing carries moisture — which helps prevent the dry mouth, dry nose, and nasal irritation that unhumidified therapy can cause.

ResMed offers the H5i tub in two versions, and the difference is how you maintain them. This standard tub is a sealed unit: simple, no parts to disassemble, and replaced on a schedule rather than deep-cleaned. The cleanable tub (36800) opens up so every internal surface can be washed and reused over a longer period.

Which is better depends on your preference: standard is lower effort per day and lower cost per unit; cleanable costs more up front but is replaced less often.

Key features

• Genuine ResMed standard tub (36803) — correct fit for the H5i humidifier.
• Sealed disposable design — no disassembly; simple periodic replacement.
• Restores proper humidification — replaces a clouded, scaled, or cracked tub.
• Simple to fit — slides into the humidifier; no tools.
• Cleanable version available — part 36800, if you prefer a reusable tub.

Specifications

Care & replacement

Empty the tub daily and refill with fresh distilled water before each use — distilled water greatly reduces mineral scale and extends the tub’s life. Clean it per the H5i user guide and let it dry completely before reassembly. Replace the tub when it becomes cloudy, heavily scaled, cracked, or no longer seals properly — commonly around every 6 months with regular use, or sooner as needed.

Standard or cleanable — which should I choose?

• Standard (36803): sealed unit, lower cost per tub, replaced more often. Best if you want simplicity.
• Cleanable (36800): opens for thorough washing, reused longer, higher up-front cost. Best if you prefer deep cleaning and fewer replacements.

Both fit the same H5i humidifier — it’s purely a maintenance preference.

Frequently asked questions

What does the water tub do?
It holds the water the humidifier heats, adding moisture to the air delivered through your tubing.

Which humidifier does it fit?
The ResMed H5i heated humidifier, used with the S9 series.

What’s the difference between 36803 and 36800?
36803 is the standard sealed (disposable) tub; 36800 is the cleanable version designed to be opened, washed, and reused.

What water should I use?
Distilled water is recommended — it reduces mineral buildup and helps the tub last longer.

How often should it be replaced?
Commonly around every 6 months with regular use, or sooner if it’s cloudy, scaled, cracked, or leaking.

Do I need a prescription?
No — replacement humidifier parts do not require a prescription.

Can I get it delivered in Brooklyn or shipped nationwide?
Yes — Stark Medical Supplies offers local pickup and delivery in Brooklyn and across NYC, plus USPS shipping throughout the continental U.S.

Use with a compatible ResMed H5i humidifier according to the device’s user guide. Use only water as directed by the manufacturer.