The short version
- 21 CFR 1250.80 applies to vessels engaged in interstate traffic. No class, tonnage or passenger threshold.
- 1250.84 requires hot and cold potable water in medical care spaces for hand-washing and medical care. Cold alone fails.
- 1250.82 requires the potable system to be separate and distinct, and names the filling hose inside that system.
- The rule is FDA, under Title 21, which is why no maritime search ever surfaces it.
- On its own query it ranks last, behind Coast Guard accommodation subparts and WHO guidance that binds nobody.
The agency that regulates your drinking water is the FDA
Ask a United States vessel operator which agency sets the sanitation rules for their potable water and the answer is usually the Coast Guard, sometimes the CDC, occasionally the World Health Organization. All three are wrong as the primary answer.
21 CFR 1250.80 states that the sanitation facilities and the sanitary conditions on vessels engaged in interstate traffic shall comply with the requirements prescribed in that subpart.[1] Part 1250 sits in Title 21, under the Food and Drug Administration.
Subpart E runs thirteen sections and covers potable water systems, water storage before treatment, water in galleys and medical care spaces, drinking fountains and ice, wash water, swimming pools, toilets and lavatories, discharge of wastes, and insect and rodent control.[5]
That single placement explains why almost nobody in the maritime industry has read it. An operator searching maritime sources will never reach a Title 21 food and drug regulation, and a search that returns FDA content usually returns drug rules, not water rules. The same blind spot hides the medical waste chain and the diving medical kit rule.
What the search results give an operator instead
A live capture in September 2026 returned, in order: the eCFR text of the Coast Guard accommodation subparts for three different subchapters, a World Health Organization Guide to Ship Sanitation chapter hosted on a National Institutes of Health bookshelf, a Coast Guard marine safety centre guidance PDF, and the FDA subpart itself in last place.
| What ranks | What it is | Why it is the wrong answer |
|---|---|---|
| 46 CFR 92.20, 72.20, 190.20, 144 subpart G | Coast Guard accommodation subparts[2] | These govern where crew live and sleep. They are construction standards, not sanitation standards |
| WHO Guide to Ship Sanitation | International guidance[3] | Guidance, not United States law. It binds nobody and creates no duty |
| USCG MSC Guidelines E1-21 | Plan review guidance for potable water systems[4] | Useful and current, but it is design review guidance, not the operating rule |
| 21 CFR part 1250 subpart E | The binding federal rule[5] | Ranks last. This is the one that actually applies |
Ranking a construction standard, a piece of international guidance and a plan review procedure above the binding rule is the same broken citation chain we recorded for uninspected vessels and for the EU chest categories. Flag state chest rules shows the same substitution running the other way.
The rule assumes you have a medical care space, and plumbs it
This is the section that matters most to a medical programme, and it is the reason a water regulation belongs on this site at all.
21 CFR 1250.84, verbatim
Potable water, hot and cold, shall be available in the galley and pantry, except that when potable water storage is inadequate, nonpotable water may be piped to the galley for deck washing and in connection with garbage disposal. Potable water, hot and cold, shall be available in medical care spaces for hand-washing and for medical care purposes excluding hydrotherapy.[6]
Read the second sentence again. A federal regulation requires hot and cold potable water in the medical care space of any vessel in interstate traffic, for hand-washing and for medical care.
It does not require the vessel to have such a space. That question is answered by 46 CFR 92.20-35 and 108.209, on a twelve person and three day trigger. But where a space exists, 1250.84 attaches to it.[6]
The practical failure is ordinary. A compartment gets designated as the treatment space because it is convenient, and it has a cold tap or none. Nothing in the usual audit catches it, because nobody is auditing against Title 21. Mobile offshore drilling units and vessels running long distances from definitive care feel it hardest, because their medical space is the only one there is.
One rule does most of the work: separate and distinct
21 CFR 1250.82 opens with a sentence that decides most real world disputes: the potable water system, including filling hose and lines, pumps, tanks and distributing pipes, shall be separate and distinct from other water systems and shall be used for no other purposes.[7]
The section then carries independent potable tanks, separation from nonpotable systems, drainage provisions, clear identification markings, prevention of backflow and cross connections, and cleaning and disinfection when ordered by the Commissioner.[7]
The filling hose is named in the text
The hose is inside the definition of the system. A potable hose used once for washdown, or stored on the same reel as a general service hose, breaks the separate and distinct requirement on its face.[7] It is the cheapest finding on this list to prevent and the most common one to create.
Wash water gets its own section at 1250.87, and toilets and lavatories at 1250.90.[8][9] Water storage before treatment sits at 1250.83, drinking fountains and ice at 1250.85 and 1250.86, and discharge of wastes at 1250.93.[5] Vessel inspection under the subpart sits at 1250.81.[10]
Interstate traffic is a wider net than operators assume
The applicability test in 1250.80 is vessels engaged in interstate traffic, not vessel class, not tonnage, not passenger count.[1] There is no exemption by size and no threshold to fall under.
The section adds one accommodation: no major structural modifications are required for existing vessels.[1] That is a construction concession, not an operating exemption. The sanitary conditions requirement still applies.
Vessels with a dive spread, which already carry a physician approved medical kit under 46 CFR 197.314, are squarely inside it. So are the classes below.
| Class | Assumes the rule misses them because | Reality |
|---|---|---|
| Commercial fishing, see the part 28 review | Part 28 says nothing about water | Part 28 is a Coast Guard rule. Title 21 is a separate net and the test is interstate traffic[1] |
| Towing, see the Subchapter M review | Subchapter M is the whole rulebook | Subchapter M does not repeal Title 21. Both apply |
| Offshore supply, see the Subchapter L review | Client standards govern | A client standard is a contract. 1250.80 is a regulation[1] |
| Small passenger, see the Subchapter T review | Day trips, so no galley | The medical care space clause has no galley condition attached[6] |
The whole subpart, in one table
Thirteen sections, and an operator can carry the lot on one page. Nothing on the open web lays them out this way.
| Section | Subject | Why it matters to a medical programme |
|---|---|---|
| 1250.80 | Applicability[1] | Interstate traffic. No size or class threshold to fall under |
| 1250.81 | Inspection[10] | The enforcement hook |
| 1250.82 | Potable water systems[7] | Separate and distinct. Does most of the work |
| 1250.84 | Water in galleys and medical care spaces[6] | The section that reaches the medical programme directly |
| 1250.87 | Wash water[8] | Hand hygiene outside the medical space |
| 1250.90 | Toilets and lavatories[9] | Infection control baseline |
| 1250.95 / .96 | Insect and rodent control[11][12] | Storage conditions around the chest |
Where this touches the medicine chest
A ship’s medicine chest is a store of drugs that assumes clean hands, clean water and a controlled space. Three of those are water questions.
Reconstituting an oral rehydration salt, irrigating a wound, washing before handling a dressing: each is a medical care purpose inside the meaning of 1250.84.[6] A chest stocked to the standard in our stocking walkthrough is only as good as the tap beside it.
Insect and rodent control at 1250.95 and 1250.96 closes the loop on storage conditions.[11][12] A chest in a compartment with a rodent problem is a contamination question before it is a compliance question, and the waste side carries its own rules again.
Six checks worth running this month
- Confirm hot AND cold potable water reaches the designated medical care space. Cold alone does not meet 1250.84.[6]
- Trace the potable filling hose. Dedicated, marked, stored apart. It is named in the text of 1250.82.[7]
- Check every identification marking on potable lines, tanks and outlets.[7]
- Look for cross connections and backflow paths to any nonpotable system.[7]
- Write the tank cleaning and disinfection record, because the Commissioner can order it and the record is the only proof it happened.[7]
- Add Title 21 part 1250 to the compliance register. If it is not on the register, nobody audits it.
None of this is clinical work, which is exactly why it goes unowned. It sits between the engineer, the master and whoever holds the medical programme, and the owner and DPA question decides which of them answers for it.
Discovery Health MD is led by Ann Jarris MD, MBA, FACEP, a board certified emergency physician. Our maritime medical consulting line puts rules like this on the register, and ship medical chest management keeps the chest beside the tap in order. Set the whole programme up the way the six decisions describe, and if you change flag note that 1250.80 attaches to interstate traffic, not to the flag. Speak to the team.
Common questions
Which agency regulates potable water on a US vessel?
The Food and Drug Administration, under 21 CFR part 1250 subpart E. Section 1250.80 states that the sanitation facilities and sanitary conditions on vessels engaged in interstate traffic shall comply with that subpart[1]. Operators usually answer Coast Guard or CDC, because the Coast Guard accommodation subparts and the WHO Guide to Ship Sanitation rank far above the binding rule in search results[2][3]. The Coast Guard MSC Guidelines E1-21 are plan review guidance, not the operating rule[4].
Does a vessel need hot water in the medical space?
Yes, where a medical care space exists. 21 CFR 1250.84 requires that potable water, hot and cold, shall be available in medical care spaces for hand-washing and for medical care purposes excluding hydrotherapy[6]. Cold water alone does not meet it. The regulation does not itself require the vessel to have such a space; that trigger sits in 46 CFR 92.20-35 and 108.209 at twelve or more persons on a voyage over three days. Read our ship hospital space article.
Which vessels does 21 CFR part 1250 subpart E apply to?
Vessels engaged in interstate traffic. Section 1250.80 sets no vessel class, tonnage or passenger threshold[1]. There is one concession: no major structural modifications are required for existing vessels, which is a construction allowance rather than an operating exemption[1]. Fishing, towing, offshore supply and small passenger operators frequently assume their own subchapter is the whole rulebook. Subchapter M and part 28 do not repeal Title 21.
Can a potable water hose be used for anything else?
No. 21 CFR 1250.82 requires that the potable water system, including filling hose and lines, pumps, tanks and distributing pipes, shall be separate and distinct from other water systems and shall be used for no other purposes[7]. The filling hose is named inside the definition of the system, so using it once for washdown or stowing it on a shared reel breaks the requirement on its face. Our consulting service puts this on the compliance register.
What else does 1250.82 require beyond separation?
Independent potable tanks, separation from nonpotable systems, drainage provisions, clear identification markings, prevention of backflow and cross connections, and cleaning and disinfection when ordered by the Commissioner[7]. The disinfection point matters operationally: the order can come, and the only proof the work was done is the record you kept. Wash water sits separately at 1250.87 and toilets and lavatories at 1250.90[8][9].
Does the WHO Guide to Ship Sanitation bind a US vessel?
No. It is international guidance and creates no United States legal duty[3]. It ranks highly because there is little competing operator-facing content, the same reason a withdrawn ILO instrument still ranks for medicine chest contents. What binds a US vessel in interstate traffic is 21 CFR part 1250 subpart E[1]. Using guidance as your compliance basis leaves the actual rule unaudited.
How does water regulation affect the ship’s medicine chest?
Directly. Reconstituting oral rehydration salts, irrigating a wound and washing before handling a dressing are all medical care purposes within 21 CFR 1250.84, which requires hot and cold potable water for them[6]. Insect and rodent control at 1250.95 and 1250.96 governs the storage conditions around the chest[11][12]. A chest stocked correctly beside an inadequate tap is still a failed programme. Our ship medical chest management service covers both.
