Pool Chemical Safety: Storage, Mixing Hazards and Safe Handling

The rules that prevent most injuries

1. Read the whole label before every use. Labels give the dose, how to add the product, the required protective gear and what not to combine it with.
2. Never mix chemicals. Not chlorine with acid, not one chlorine product with another, not old product with new product of the same type. Strong reactions can create heat, fire or toxic gas. This includes residue in a scoop or bucket.
3. Add chemicals to water, never water to chemicals. Pouring water onto a dry chemical or into concentrated acid can cause violent reactions and splattering.
4. Wear protection. Splash goggles and chemical-resistant gloves at minimum, plus long sleeves and closed shoes. CDC also lists masks for handling chemicals. A pair of chemical splash goggles stored next to the products is a small habit that prevents serious eye injuries.
5. Face away and stay upwind when opening containers or adding product, and work in a well-ventilated area.
6. Keep children and pets away from chemicals and from the pool while you dose.

Storage

CDC's pool chemical safety guidance and the National Pesticide Information Center agree on the basics:

• Keep each product in its original, labeled container, tightly closed. Never transfer chemicals into drink bottles or unlabeled containers.
• Store products separately, each in its own dedicated spot, with incompatible chemicals (chlorine products and acids especially) well apart. Don't stack liquids above other chemicals where a leak could drip onto them.
• Keep them dry and cool: CDC advises storage below 95°F (35°C), out of direct sunlight, protected from getting wet, off the floor and away from doors and windows.
• Keep them away from flammables such as gasoline, oil, fertilizer, paint and solvents, and away from mowers, grills and other ignition sources.
• Lock them up where children and pets cannot reach, ideally in a ventilated shed or garage, never with food, animal feed or medicines.

Handling and dosing

• Use a clean, dry scoop or measuring cup dedicated to one chemical. Label it.
• Measure carefully using a calculator such as our chlorine dose calculator or alkalinity and calcium calculator. Overdosing is a common cause of eye and skin irritation.
• Add products one at a time, directly to the pool with the pump running, at different spots and with time between them.
• Keep people out of the water until the product has mixed and levels are back in the recommended range.
• Never put chemicals in a skimmer that holds chlorine tablets.

Spills and disposal

• Clean up spills immediately, following the label. Keep dry products dry, and never sweep spilled chlorine into a trash can with other waste.
• Don't put old, unlabeled or damaged products in household trash. Contact your local household hazardous waste program or the manufacturer for disposal instructions.
• Inspect containers after use for cracks or damaged lids.

Why it matters

CDC's review of pool chemical-related health events found that most injuries involved preventable situations: mixing incompatible chemicals, handling without protective equipment, children getting access to chemicals, and pre-dissolving or adding water to chemicals. Following the label and the steps above removes most of that risk.

A pre-dose checklist

Before you open any container, run through this list:

1. I know my pool's volume and I have calculated the dose.
2. I have read this product's label today.
3. I am wearing goggles and gloves.
4. My scoop or cup is dry, clean and used only for this product.
5. The pump is running and nobody is in the water.
6. I am adding this product on its own, with no other chemical going in for a while.
7. The container will go straight back to its own storage spot, closed.

Transporting chemicals home

Carry pool chemicals upright and separated in your vehicle, away from the passenger area if possible, and never next to each other in the same bag or box. Heat and a leaking lid can start a reaction in a closed car, so take them straight home and put them away.

Common questions

What happens if you mix chlorine and acid?

Chlorine products and acids react to release chlorine gas, which harms the lungs and eyes. Keep them in separate places, use separate measuring cups, and add them to the pool at different times.

Can I store chlorine tablets and liquid chlorine together?

No. CDC and state guidance say to separate chlorine products from one another (liquid chlorine, cal-hypo and stabilized chlorine such as trichlor or dichlor), as well as from acids.