Detection limit

A number of different detection limits have been defined: IDL (instrument detection limit), is the constituent concentration that produces a signal greater than five times the signal to noise ratio of the instrument; MDL (method detection limit) is the constituent concentration that, when processed through a complete method, produces a signal with a 99 percent probability that it is different from a blank; PQL (practical quantification limit) is the lowest constituent concentration achievable among laboratories within specified limits during routine laboratory operations, The ratios of these limits are approximately: IDL:MDL:PQL = 1:4:20.

Disinfection by-products

A range of organic and inorganic products resulting from the reaction of disinfecting oxidants with natural aquatic organic material reductants in water systems. The number and nature of all products are not precisely known at present, and vary with type of disinfectant employed. Some of the chlorination by-products are mutagenic (3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone) in the histidine reversion assay, and some are suspected animal carcinogens (Chloroform, and perhaps the entire family of trihalomethanes). Many disinfection by-products are of little or no toxicological significance, such as the non-halogen containing organic oxidation products and the simple halide ion reduction products.


Dissolved organic carbon.

Domestic wastewater

Sewage derived principally from human sources.

Enteric viruses

A large group of viruses that are characterized by the fact that they replicate in the intestinal tract and are therefore present in fetal material.


A specific group of enteric viruses that includes polioviruses, echoviruses, coxsackie viruses.

Entries to storm drainage

Water (relatively clean or polluted) discharged into a stormwater drain from sources such as, but not limited to, direct industrial or sanitary wastewater connections, roof leaders, yard and area drains, cooling water connections, manhole covers, ground water or subterraneous stormwater infiltration, etc.

Flow line

The general path that a particle of water follows under laminar flow conditions.


inanimate objects that might be contaminated with infectious organisms and thus serve to transmit disease.

Ground water

That part of the subsurface water that is in the saturated zone.

Ground water mining

The withdrawal of ground water through wells, resuiting in a lowering of the ground water table at a rate faster than the rate at which the ground water reservoir can be recharged.

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