Carboy With Stop Cock, Plastic

Quick Answer: A plastic carboy with stopcock is a large, handled storage container with a tap fitted near its base, used to hold distilled water, buffers or stock solutions and dispense them by gravity. The tap removes the need to lift and tip a heavy, full vessel.

How a Tap-Fitted Carboy Changes the Bench Routine

A full carboy is heavy, and pouring from one means lifting it, tilting it and hoping the stream lands in the neck of a small bottle. Fitting a stopcock low on the body turns the carboy into a reservoir that stays put on a shelf or bench edge. Students fill beakers and measuring cylinders by opening the tap, and the bulk liquid is never disturbed or contaminated by pipettes and funnels dipped into it.

The listing photo is of a polypropylene carboy with moulded handles, while the title itself says only plastic, so the resin and the stopcock material should be confirmed. Polypropylene containers are generally autoclavable at 121 °C and high-density polyethylene ones generally are not, which matters if the carboy will hold sterilised water. Either plastic copes well with dilute acids, alkalis and aqueous salt solutions.

A carboy without a tap, such as the plain plastic carboy in the Lab Glassware range, suits long-term storage and transport; this version suits daily dispensing. Loosen the top cap slightly while the tap is running, otherwise air cannot replace the outflowing liquid and the flow slows to a glug.

Applications

• Holding the day’s supply of distilled or deionised water in a teaching lab, so that wash bottles are refilled straight from the tap
• Storing prepared buffer or dilute stock solutions, such as physiological saline for biology practicals
• Collecting water from a still or deionisation unit and dispensing it where it is needed
• Supplying one reagent, for example limewater, to a whole class without repeated pouring from a large bottle

Specifications

Care & Handling

• Stand the carboy with the stopcock overhanging the shelf edge or on a raised block, so a beaker or bottle fits beneath the tap.
• Check the stopcock for drips after the first filling and before leaving the carboy unattended overnight.
• Clean with dilute laboratory detergent and rinse well; for distilled water, a periodic drain and rinse limits algal or bacterial film on the walls.
• Keep organic solvents out of the carboy until both the resin and the stopcock seals have been checked against the solvent.

Why Choose LabEquip

Lab technicians and school science departments buy carboys like this to keep a bulk supply of water or reagent in one place. LabEquip lists it with other chemistry lab equipment; to confirm capacity and material for your storage needs, write through the contact page.

Frequently Asked Questions

Why does the flow slow down after the tap has been open for a while?

Liquid leaving the tap must be replaced by air entering at the top. If the cap is screwed down tightly, a partial vacuum forms inside and the flow becomes weak and irregular. Loosening the cap a quarter turn, or fitting a vented cap, restores a steady stream.

Can a plastic carboy with stopcock be autoclaved?

Polypropylene carboys generally withstand autoclaving at 121 °C, but polyethylene ones generally do not, and the stopcock parts must also tolerate the heat. Confirm the material of both before autoclaving, and always loosen the cap so pressure can equalise.

Is it suitable for storing distilled water long term?

Yes. Plastic carboys are widely used for distilled and deionised water. Keep the cap on to reduce dust and carbon dioxide uptake, and empty, rinse and refill the carboy regularly rather than topping it up indefinitely.

Which liquids should not be kept in a plastic carboy?

Avoid strong oxidising acids such as concentrated nitric acid, and many organic solvents, including chlorinated and aromatic ones, unless the plastic is known to resist them. Aqueous solutions, dilute acids and dilute alkalis are the usual contents.

How should the carboy be placed for dispensing?

Set it on a stable shelf or raised platform with the tap clear of the edge, so a receiving vessel can sit underneath. Never move a full carboy by the stopcock or lift it above shoulder height; move it empty and fill it in place.

How is the carboy cleaned?

Drain it through the tap, rinse with warm water and a mild laboratory detergent, then rinse several times with distilled water. Open and flush the stopcock during cleaning so detergent does not remain in the tap body.

Last Updated: September 2026