Dechlorination Calculator

Inputs

Large screens show three columns, smaller two, mobile one.

Water Volume

Total water you will treat.

Volume Unit

Converted to liters internally.

Disinfectant Type

Check your local water report if unsure.

Initial Chlorine (mg/L)

Often 0.2–4.0 mg/L for tap water.

Target Chlorine (mg/L)

Use 0.0–0.1 mg/L for sensitive plants.

Safety Factor (%)

Adds a margin for measurement uncertainty.

Choose Methods

Sodium thiosulfate

Vitamin C

Activated carbon

Aeration / waiting

If you select none, the calculator will show all methods.

Thiosulfate Form

Form changes dose by molar mass.

Vitamin C Type

Sodium ascorbate is less acidic.

Chloramine Multiplier

Used only when chloramine is selected.

Powder Density (g per teaspoon)

Helps estimate teaspoons for Vitamin C.

Carbon Capacity (mg per g)

Set based on your carbon spec sheet.

Carbon Contact Time (min)

Longer contact improves removal.

Aeration Scenario

Only used for free chlorine estimates.

Custom Half-life (hours, optional)

Overrides the scenario value if set.

Reset

Example Data Table

Typical ranges; test your water for best accuracy.

Scenario	Water Volume	Initial (mg/L)	Target (mg/L)	Method to try
Seedling tray refill	10 L	1.5	0.1	Vitamin C or aeration
Raised bed watering can	5 US gal	2.0	0.0	Thiosulfate or carbon
Drip tank top-up	200 L	0.8	0.1	Carbon filtration

Formula Used

Chlorine to remove (mg/L): max(C_initial − C_target, 0)
Total chlorine mass (mg): (mg/L) × Volume_L
Dose (mg): Total_mg × Factor × TypeMultiplier × SafetyMultiplier
Safety multiplier: 1 + (Safety% / 100)
Aeration estimate (free chlorine): exponential decay with half-life, t = half_life × log2(C_initial / C_target) (near-zero uses 0.02 mg/L)

Dosing factors vary by product and water chemistry. Always validate using a chlorine test strip before watering sensitive plants.

How to Use