One of the most widely used testing methods for free and total chlorine makes use of something known as ‘DPD’ which stands for N,N Diethyl-1,4 Phenylenediamine Sulfate. The addition of DPD to water samples containing oxidizers such as free chlorine, bromine, iodine, chlorine dioxide and/or permanganate results in the formation of a reddish tint to the water whose intensity directly relates to the amount of oxidizer(s) present in the water sample.

At low oxidizer concentrations water samples turn a slight shade of pink in the presence of DPD and at higher oxidizer concentrations the sample will turn blood-red orange. In extremely high concentrations of oxidizers, as in above 10 ppm, the sample will turn blood-red and then go crystal clear due to the bleaching effect of the oxidizer(s) it contains.

Other oxidizers such as ozone and total chlorine do not react directly with DPD and require the addition of a compound known as Potassium Iodide (KI) before they will react with DPD.

• DPD-1 — Used to test oxidizer levels in water samples containing free chlorine, bromine, iodine, chlorine dioxide and/or permanganate.
• DPD-3 — Useless on its own, but when added to samples already containing DPD-1 and free chlorine, total chlorine, bromine, iodine, chlorine dioxide, permanganate and/or ozone, pink through blood-red color development will occur in the sample.
• DPD-4 — The combination of DPD-1 (N,N Diethyl-1,4 Phenylenediamine Sulfate) and DPD-3 (KI) to samples containing free chlorine, total chlorine, bromine, iodine, chlorine dioxide, permanganate and/or ozone will result in pink through blood-red color development in the sample. Simply put, DPD-1 + DPD-3 = DPD-4.

DPD comes in various forms, the most common of which include tablets, powder pillows, liquids and ReagentStrips^TM. Each works equally well when used correctly and may typically be interchanged with one another, though all do have their pros and cons.

• Tablets: One of the cheapest forms of DPD available and has a very long shelf-life. Difficult to break apart and dissolve in cold or hard water samples and may leave suspended solids floating around in samples.
• Powder Pillows: Inexpensive form of DPD. Difficult to dissolve in cold or hard water samples and may leave suspended solids floating around in samples. Users also complain of ‘annoyance value’ associated with having to tear the foil pillows open and pour the DPD powder into the sample vials. Not well-suited for outdoor testing.
• Liquids: Shorter shelf-life and much more unstable than other forms of DPD, considered ‘messy’ by many users, but also probably the expensive form of DPD.
• ReagentStrips^TM: Convenient delivery method for DPD, rarely leaves undissolved solids in samples regardless of temperature or hardness, decent shelf-life, and available in bottles of 50 or individually wrapped tests (excellent for field work).

An article published in the Health section of the http://www.dailymail.co.uk web site on June 2, 2008 stated that a study done at Birmingham University (in England) found a correlation between pregnant women drinking certain types of tap water and the occurence of serious birth defects in their unborn children.

“Drinking or even showering in tap water can double the risk of having deformed children,” says study.

Drinking tap water while pregnant may double the risk of serious heart or brain defects in the unborn child, research suggests.

A study of almost 400,000 babies found a clear link between chemicals formed during chlorination and the occurrence of a trio of birth defects.

Drinking water, showers, swimming pools and even the steam from a boiling kettle can all contain the problem chemicals called trihalomethanes, or THMs, the researchers said.

While the study was carried out in Taiwan, it is thought up to one in six British homes is exposed to levels even higher than those found to cause concern, with concentrations tending to be particularly high in the spring and autumn.

The researchers stressed it would be impractical for pregnant women to avoid tap water and said the onus was instead on the use of disinfection methods which limit levels of the chemicals.

The Birmingham University study compared details of birth defects with the level of THMs in tap water.

The analysis of almost 400,000 babies showed those born into regions where levels were around 80 per cent more likely to have a hole-in-the-heart defect and more than 50 per cent more likely to have a cleft palate.

Their odds of suffering anencephalus - a condition that causes much of the brain, skull and scalp to be missing - were almost doubled, the journal Environmental Health reports.

While birth defects are rare - occurring in about 2 per cent of births - the three flagged up in the study are among the most common.

It is thought the chemicals may harm the unborn baby directly. Alternatively they may damage the woman’s eggs. Although the study did not prove that the chemicals caused the birth defects, it is not the first to make the link.

Researcher Professor Jouni Jaakkola said: ‘Our findings don’t just add to the evidence that water chlorination may cause birth defects, but suggest that exposure to chlorination byproducts may be responsible for some specific and common defects.

THMs are the products of a chemical reaction between chlorine and organic compounds common in lakes, rivers and reservoirs.

The amount of THMs made during chlorination vary according to where the water comes from and the disinfection process, meaning highly chlorinated water does not necessarily have the highest levels.

Home water filters may not be entirely effective at removing the chemicals and bottled water may also be tainted.

Professor Jaakkola said the solution was for water companies to use disinfection procedures that keep the production of THMs to a minimum.

He said: ‘Water disinfection has an important purpose in reducing microbial load and reducing acute gastro-intestinal infections.

‘Some have claimed it is the best public health measure ever introduced.

‘We are talking about rare health effects and a modest risk increase.

‘I don’t suggest stopping using tap water but we have to be conscious that at population level some risks may be related to increased levels.’

The Drinking Water Inspectorate, which is tasked by the Government to monitor the safety of tap water, said its own, larger-scale research had failed to find a link between THMs and birth defects.

Principal inspector Sue Pennison said: ‘Obviously we will review this research, engage our health expert colleagues, and look to see if it means we need to do anything more. But there’s no reason for people to be worried.

‘Chlorination is reliable and has been used for centuries. The only reason diseases like cholera and typhoid are not in our water supply is because of chlorination.’

The water industry trade body, Water UK, said it would consider the findings but chlorination in the UK meets World Health Organisation guidelines. ( source )

Testing for Disinfection Byproducts?

There are no ’simple’ ways to test for disinfectionm byproducts (DBP’s), but homeowners can find out if the water supplied by their public water systems possibly contains disinfection byproducts by using a test kit like the WaterWorks^TM Free and Total Chlorine Test Kit. See below:

WaterWorks^TM 2 Free and Total Chlorine

The test strips above have two pads: 1 for measuring Free Chlorine Residual and 1 for measuring Total Chlorine Residual.

• No Color on Either Pad: This typically means the water contains no chlorine at all. If on a residential water system, a person may want to re-test and/or consult your local water authority. Please note, though, that the absence of free and total chlorine does NOT necessarily mean the water does not contain disinfection byproducts. A possibility exists that all of the chlorine (or chloramines) added at the water treatment plant have left the water before getting to where it was drawn for testing.
• Color on Both Pads: This means both free and total chlorine exist in the sample water and a possibility exists that the water also contains disinfection byproducts.
• Color on Free Chlorine Pad Only: This should not ever happen because the total chlorine concentration represents the sum of the free chlorine plus the combined chlorine in the water. You cannot have free chlorine registering w/o it also registering as part the total chlorine concentration.
• Color on Total Chlorine Pad Only: If the public water system uses a chlorine/ammonia based disinfectant system then the water will more than likely NOT contain disinfection byproducts. If, however, the public water system uses a free chlorine residual as its disinfectant, then a good chance exists that the water contains disinfection byproducts.

Don’t forget that you can always find out definitively whether or not your tap water contains disinfection byproducts by simply calling your local water company and asking questions. As a general rule, the law requires them to divulge that sort of information upon request to anyone who asks.

Per the request of several men and women currently serving in the United States Armed Forces and other branches of the Unites States Government, we will begin posting possible alternate products for popular (established) NSN’s (National Stock Numbers) related to water quality testing.

6640014907587 — Chlorine Test Paper

“BOTTLES OF 50. DETECTION RANGE OF 0PPM TO 10PPM. HACH.”

Alternatives:

• Chlorine Test Strips — Easy to use dip and read test strips for free and total chlorine. Detection ranges vary, but can start at low as .005ppm and reach as high as 2,000ppm. Packaged in bottles of 50 or individually wrapped in foil packs.

The above link will take you to a general chlorine test strip page listing a number of different products but if you know more precisely the range of detection you require, the links below will take you directly the chlorine testing product best suiting your needs:

Free Chlorine Test Strips:

• Range: 0 ppm to 6 ppm
• Range: 0 ppm to 25 ppm
• Range: 0 ppm to 80 ppm
• Range: 0 ppm to 120 ppm
• Range: 0 ppm to 750 ppm
• Range: 0 ppm to 2,000 ppm

Total Chlorine Test Strips:

• Range: 0.005 ppm to 0.2 ppm
• Range: 0 ppm to 10 ppm
• Range: 0 ppm to 80 ppm

Free and Total Chlorine Test Strips:

• Range: 0 ppm to 5 ppm

Whether you need to test for high levels of chlorine or test for low levels of chlorine, rest assured that reliable, safe and easy-to-use test strips from Industrial Test Systems, Inc. can and WILL get the job done right each and every time.

Note: We have found that the products suggested above meet or exceed the specifications of the original NSN (National Stock Number) item. This does not mean, though, that you may substitute them in place of the item on a Government Contract. We provided the above information as possible sources of water quality testing products for consideration in future Contracts/Bids only.

Per the request of several men and women currently serving in the United States Armed Forces and other branches of the Unites States Government, we will begin posting possible alternate products for popular (established) NSN’s (National Stock Numbers) related to water quality testing.

NSN: 6550012191061, 6550014257957 — Chlorine Test Tablets

“DPD REAGENT TEST TABLETS FOR CHLORINE ANALYSIS. PACKAGED IN INCREMENTS OF 100. LAMOTTE.”

Alternatives:

• DPD 1, 3 and 4 ReagentStrips — Faster and more convenient than traditional DPD test tablets. No MSDS required. Safe to use on production room floors of food processing facilities. EPA Compliant testing method. Packaged in bottles of 50 or individually wrapped in foil packs. Costs as low as 8 cents a test.

eXact^® Strip DPD ReagentStrips

Note: We have found that the products suggested above meet or exceed the specifications of the original NSN (National Stock Number) item. This does not mean, though, that you may substitute them in place of the item on a Government Contract. We provided the above information as possible sources of water quality testing products for consideration in future Contracts/Bids only.

The term biguanide refers to a sanitizer that uses a complex polymer as its base rather than traditional chlorine or bromine molecules. Use of a biguanide sanitizer elimiates the offensive ‘chemical smell in a pool/spa, puts a stop to the bleaching of hair and swimwear, reduces eye irritation and makes it possible for those with allergic reaction to chlorine or bromine to enjoy a dip in the pool/spa.

Mixing Biguanide With Chlorine/Bromine?

A definite no-no. The chlorine or bromine will destroy the biguanide polymer and in some cases cause insightly preciptates to fall out of solution. You will NOT enjoy cleaning up a pool or spa in which biguanides have met up with oxidizers such as chlorine or bromine.

Switching Between Biguanide and Chlorine/Bromine Sanitizers?

For those who seek to switch from a biguanide system to chlorine/bromine system, or vice versa, make certain you remove ALL of the former system’s chemicals before adding the new system’s chemicals.

In the case where a person wants to switch from a chlorine/bromine system over to a biguanide system, they should perform a test for Total Chlorine/Bromine before adding any of the biguanide chemicals. Test strips work well for this application and pool/spa owners can choose from a number of multi-parameter test strips to get the job done:

• Pool Check 6-in-1: free chlorine, total chlorine/bromine, pH, total alkalinity, total hardness, cyanuric acid
• Pool Check 5-in-1: free chlorine, total chlorine/bromine, pH, total alkalinity, total hardness
• Pool Check 4-in-1: free chlorine, total chlorine/bromine, pH, total alkalinity
• Pool Check Low Chlorine 3-in-1: free chlorine, pH, total alkalinity

And for those who REALLY want to make sure no chlorine resides in thei water, try using the WaterWorks^TM Ultra Low Total Chlorine Strips. Their lowest detection block starts at 0.005ppm total chlorine — an incredibly detection level for a dip and read test strip!

Just as growers of plants must watch over their fields, so must they monitor the chlorine levels in the water they use to irrigate their fields.

Ideally for the farmer, the water going into the ground and/or getting sprayed over his fields should contain as low a disinfectant concentration as possible since chlorine kills more than just microorganisms. In too great a concentration it destroys plantlife as well.

How Can Farmers Monitor Chlorine Levels?

While several methods for testing chlorine levels in farm water exist, and all have merit, the simplest chlorine level testing method for farmers comes in the form of dip-n-read test strips. They require no formal training, cost very little, and give fast, accurate results typically in under a minute. See below for examples of test strips well suited for testing chlorine levels in farm water:

Do Farmers Test for Free Chlorine or Total Chlorine in Farm Water?

Most farmers test for total chlorine in farm/irrigation water. The total chlorine concentration includes the free chlorine residual and the combined chlorine (chloramine) residual. Both free chlorine and combined chlorine can function as oxidizers, though free chlorine typically does work much more effectively.

SenSafe Total Chlorine Test Strips (0ppm to 10ppm)

While many water professionals worry about getting chlorine into water and establishing a chlorine residual, other water professionals worry about removing chlorine from water.

• Example 1: Before water from a well can pass a coliform bacteria test at a certified laboratory and get approved for human consumption it must test as having absolutely no chlorine residual in it.

• Example 2: Federal, State and Local Environmental Laws/Regulations prohibit the discharging of highly chlorinated water from a wastewater treatment facility or from any other water processing facility. Chlorine, even in low concentrations, poses a serious danger to the ecosystem and the releasing of too large an amount into environment can wipe out the area’s vegetation and animal life very rapidly.

What Type of Chlorine Should One Test For?

Typically speaking, when concerned about the amount of chlorine residual in the discharge from any sort of wastewater treatment facility, most people check for total chlorine. Testing solely for free chlorine would not suffice for environmental purposes because combined chlorine, also called chloramines, can still have harmful effects on the environment despite not having the as great an oxidation potential as free chlorine.

How Can One Test for Low Levels of Total Chlorine?

Test Strips: Quick, easy and cost effective. Test strip methods for chlorine concentration determination offer extreme amounts of convenience and require little or no technical training. Just dip the strip and compare the color of the test area to a color chart. (total chlorine, ultra low total chlorine)

DPD: Typically used in conjunction with a colorimeter, DPD methods for chlorine concentration determination give more precise results than most visual methods, but as stated, they typically require the use of instrumentation (see DPD ReagentStrips, eXact EZ, Chlorometer 1000). For environmental compliance monitoring and reporting purposes, most government bodies require the use of an EPA Compliant DPD testing method.

Titrations: A time consuming method which typically uses DPD in liquid form and requires a certain amount of laboratory skills. Not very practical for field work.

That all depends on who you talk to. Most public water systems using chlorine as their primary disinfectant typically try to have a free chlorine residual flowing through their lines all the way to your faucet. Other public water systems using chlorine as their primary disinfectant try to have a chloramine residual flowing through their lines all the way to your faucet.

Determining the Chlorination System Your Water Supplier Uses

Chlorine Smell Test: In general, water containing only chloramines gives off a much more objectionable odor than water containing a free chlorine residual. While true that a free chlorine system generates chloramines as the free chlorine gets used up fighting whatever biological contaminants it encounters, the amount of odor given off by those chloramines will typically not surpass the amount of odor given off by water treated solely with chloramines.

Home Water Testing: While no test strip exists to check JUST the chloramine concentration in water, one does exist to check both the Free Chlorine Residual and the Total Chlorine Residual: The WaterWorks 2 Free & Total Chlorine Strip accurately measures both parameters with a single water quality test strip.

WaterWorks 2 Free and Total Chlorine Home Water Test Kit

• If the free chlorine test area shows color AND the total chlorine test area shows color, then your water supplier most likely uses free chlorine as its primary disinfectant.

• If the free chlorine test area does not show color BUT the total chlorine test area does not show color, then your water supplier most likely uses chloramines as its primary disinfectant.

Although the above testing method will yield quality results, calling your local water supplier will get you the same information.

In reponse to recent emails, we will re-visit the topic of free chlorine versus combined chlorine and how they both relate to total chlorine:

(Free Chlorine) + (Combined Chlorine) = (Total Chlorine)

Free Chlorine: Typically your main sanitizing/disinfecting agent and sometimes referred to as ‘available chlorine’. In most cases people try to keep a free chlorine residual in their water to act as a buffer against biological contaminants. Chemically speaking this is the amount of hypochlorous acid and hypochlorite ion in solution. find free chlorine test strips

Combined Chlorine: The resulting compound when free chlorine molecules interact with biological contaminants containing Nitrogen which most people refer to as ‘chloramines’. You could also refer to combined chlorine as ‘used free chlorine’, but keep in mind that it still does have the abiity to act as a sanitizer/disinfectant… just not nearly as effectively.  find total chlorine test strips

Total Chlorine: The sum of all free, ‘available’, combined, and ‘used’ chlorine in solution.  find total chlorine test strips

A reagent (chemical) known affectionately as DPD has reigned supreme as the ‘best’ way to test for the presence of free or total chlorine in water for quite a while now.  What most folks don’t know is that someone has FINALLY found a way to make using DPD cost-effective and convenient.

DPD ReagentStrips:  Looks like a test strip, but functions like a totally convenient way to precisely administer measured amounts of DPD into a 10 mL water sample.  All the reagents, buffers and indicators come neatly impregnated on the pads at the end of an ergonomic PVC strip.  Simply swish the pads around in your sample for 20 seconds, remove the strip, throw it away, and read your sample in your preferred colorimeter.  DPD ReagentStrips fall under the guidelines of EPA Compliance and may be used in place of all other DPD methods. . . and they don’t require MSDS.

Also, at approximately $0.08 per test (USD), the DPD ReagentStrips make staying in strict compliance with EPA guidelines for chlorine detection quite affordable.

Previously, DPD came in one of three forms: powder pillow, tablet or liquid.  Each has its benefits. . . and each has its downfalls.

Powder Pillow:  The most popular form of DPD.  Precise amounts of the reagent come in single-dose foil ‘pouches’ that the user tears open and pours into their sample.  Sounds like a great idea, yes, but try using these things in a ‘wet’ or windy environment.  Anyone who works in the field will know what that means.  MSDS required.

Liquids:  Cheap as can be, but with that inexpensive price comes an incredibly short shelf-life compared to other DPD delivery systems.  MSDS required.

Tablets:  Very inexpensive, very stable.  Great way to deliver exact amounts of DPD into samples, except for one small problem:  DPD tablets do not dissolve smoothly or easily in cold or hard water.  In either type of water, DPD tablets typically leave undissolved solids floating in the sample and in colorimeters, these can lead to erroneous readings.

Fast Dissolving DPD Tablets:  Same as above, but they can leave other materials in the sample:  Elements of the binding agent which held the tablets together prior to immersion in the sample.

So as you can see, older methods of DPD delivery have met their match.  For more information and even to receive free samples, check out the Industrial Test Systems, Inc. web site.  This is one free and total chlorine testing innovation you don’t want to miss out on!