Turbidity Removal Efficiency Calculator

Work out turbidity removal efficiency instantly with clear inputs, formula shown and shareable results.

About Turbidity Removal Efficiency Calculator

Turbidity removal is assessed stage by stage because each barrier has its own performance expectation: clarification should achieve 85-95% removal to deliver settled water below 5 NTU, and filtration should then produce under 0.3 NTU. Filtered turbidity is a surrogate for pathogen removal, which is why it is regulated so tightly.

Formula

Removal efficiency

Removal % = (inlet - outlet) x 100 / inlet, applied at each stage

Worked example

With the default values below, Turbidity Removal Efficiency Calculator returns Overall Turbidity Removal of 99.6667%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Raw Water Turbidityminimum 0 NTU: 45 NTU
Settled Water Turbidityminimum 0 NTU: 4 NTU
Filtered Water Turbidityminimum 0 NTU: 0.15 NTU
Regulatory Limitminimum 0 NTU: 0.3 NTU

Results

Overall Turbidity Removal: 99.6667%
Clarifier Removal: 91.111%
Filter Removal: 96.250%
Compliance Status: Compliant with turbidity limit

Step by step

1Values used
2Removal efficiency
3Overall Turbidity Removal= 99.6667
4Clarifier Removal= 91.111
5Filter Removal= 96.250
6Compliance Status= Compliant with turbidity limit

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 4 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
Filtered water turbidity is a regulated critical parameter monitored continuously. Exceedances require notification and may require a boil-water advisory.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Filtered water turbidity is a regulated critical parameter monitored continuously. Exceedances require notification and may require a boil-water advisory.

Frequently Asked Questions

Why is 0.3 NTU the common limit?

Because filtered turbidity correlates with removal of Cryptosporidium oocysts and Giardia cysts, which are chlorine resistant. Turbidity is the practical continuous surrogate for that barrier's integrity.

What does a turbidity spike indicate?

Filter breakthrough or a coagulation upset, and a possible pathogen passage event. Post-backwash turbidity spikes are a particular risk and are managed with filter-to-waste.