While the average person does not have a need to for chlorine levels much above 3 to 5 parts per million, and even then they would typically only need to do so to make sure their swimming pools had a sufficient amount of free chlorine, but other folks have the need to test for free chlorine levels in excess of 25 or 50 parts per million on a regular basis. Below we will list a few of the places where you might expect to see a need for high range free chlorine testing.

Fruit & Vegetable Processing

After fresh produce leaves the fields it travels to a processing facility where it typically gets washed with a solution containing some sort of sanitizer such as chlorine, ozone, etc. In cases where the produce processing plant uses chlorine employees must make sure the rinse water contains a certain amount of free chlorine after it has passed over the fruit/vegetables.

Levels of free chlorine drop with an increase in biological load (contamination) and the rinse water having free chlorine left after use indicates that the produce no longer contains biological contamination on its surfaces.

Childcare Facilities

State laws require that childcare facilities clean their surfaces with properly mixed sanitizing and disinfecting solutions that contain an appropriate concentration of sanitizing or disinfecting chemicals. In many cases these facilities use chlorine bleach solutions for cleaning purposes.

As a general rule these solutions must contain anywhere from 50 to 200 parts per million free chlorine for sanitizing solutions and anywhere from 500 to 800 parts per million free chlorine for disinfecting solutions. In case like this the Waterworks High Range Free Chlorine Test Strips will not work because they have an upper detection limit of only 120 parts per million free chlorine, but WaterWorks Free Chlorine Check Ultra High II has an upper detection limit of 2,000 parts per million free chlorine and works well in this application.

Some states leave it up to individual childcare facilities to determine testing frequency of sanitizing and disinfecting solutions while other states, like North Carolina for example, have strict laws dictating how often childcare facilities must perform testing.

As of January 1, 2006, all licensed, non-in-home daycare centers in the State of North Carolina had to have the ability to test the chlorine bleach content in both their sanitizing and their disinfecting solutions. Previously the law stated that they had to test only the chlorine concentration in their sanitizing solutions. ( source )

If interested in purchasing a test kit for testing sanitizing & disinfecting solutions in a childcare facility, you can find them readily available on the Filters Fast web site.

Water Lines and Water Mains

Before a water line can go into service for the first time or go back into service after a breakage or leak has gotten repaired technicians must flush (burn) the lines with water containing a high concentration of free chlorine to clean out any and biological contaminants. Typically the technicians must test the discharge water periodically until the free chlorine level remains constant at a high level for a set amount of time.

Waterworks High Range Free Chlorine Test Strips work very well for this application.

Product-specific information about Waterworks High Range Free Chlorine Test Strips:

• Testing requires just 32 seconds
• Each bottle contains 50 ready-to-use tests
• Color chart has easily distinguished color blocks at 1, 5, 10, 20, 40, 80, 120 ppm
• No harmful chemicals or reagents to handle

Whether you need a basic test kit for chlorine & pH, a set of easy-to-use chlorine test strips, or an electronic chlorine testing meter, you will find the product to suit your testing needs on ChlorineTests.Com.

You can also find replacement reagents for several different chlorine test kits on ChlorineTests.Com, which naturally means you will find DPD tablets on the site for sure.

And now for a few basic chlorine testing facts:

• Test kits containing only OTO as their chlorine testing reagent will test for total chlorine only.

• Free chlorine testing requires DPD-1. Adding DPD-3 to the sample after adding DPD-1 allows a person to test for total chlorine.

• The USEPA has set the maximum contaminant level for chlorine in drinking water at 4.0ppm. This limit applies to both free chlorine levels and total chlorine levels.

• When testing for parameters other than chlorine, some test kits will require the use of chlorine eliminating agents such as sodium thiosulfate before testing can take place.

• Water containing the same amount of total chlorine as it does has very little or no free chlorine.

• The difference between the free chlorine level and the total chlorine level equals the chloramine concentration.

With so many news stories surfacing about pool water and/or drinking water not having adequate disinfectant levels many health officials have started pushing for increased testing and they don’t mean testing for chlorine residuals with test strips or liquid test kits which both require testers to match colors to get readings.

Rather than trust test personnel to use established methods of chlorine testing such as the Taylor FAS DPD Test Kit and/or the recently EPA Approved SenSafe Free Chlorine Water Check product, some folks want to remove as much subjectivity from the chlorine testing process as possible… and that means using meters to test chlorine residuals.

One example of a meter that some folks have turned to goes by the name of Extech (CL200) Exstik Direct Digital Reading Chlorine Meter and you can see a picture of that meter to the left.

The Extech CL200 Chlorine Testing Meter tests only for TOTAL chlorine, uses DPD as its reagent, requires roughly 2 minutes for testing, stores up to 15 readings internally, and detects total chlorine levels down to 0.01ppm (mg/L).

Extech, the manufacturer, claims the EPA has deemed the meter, with its associated DPD testing method, acceptable for wastewater compliance monitoring of Total Chlorine.

From what we can see on the IsoPureWater web site, this meter cannot used generic DPD tablets, DPD powder pillows, or DPD liquids designed for 10 mL sample sizes… and that means having fewer shopping options when the time comes to acquire replacement DPD reagents.

Not necessarily a show-stopper by any stretch of the imagination since a pack of 100 DPD reagent tablets for this meter costs under $30.

Definitely keep this meter in mind should you need a fast, compact meter for testing total chlorine levels in water.

A plethora of health-related problems afflict many people living in Africa and many of those health conditions stem from the fact that the continent lacks an infrastructure capable of delivering clean, safe drinking water to many of its residents.

With that in mind, please excuse our departure from the normal subject matter and indulge us as we answer a question about purchasing DPD test tablets for chlorine testing in Zambia, an African Nation.

“Robert K” asked…

I need to know if there is company in Zambia or Sub-sahara Africa selling DPD #1 tablets.

This is a very informative site, keep it up

Thank you, Robert, for contacting Water Testing Blog with this question. We don’t know a whole lot about companies doing business with other areas of the world such as Zambia, but we did find a few links that may prove useful information.

• http://www.wisa.org.za/Home/Home.htm — Water Institute of Southern Africa

• http://www.smianalytical.co.za/water-analysis.html– SMI Analytical Services Provides Water Testing Services to South Africa

• http://www.merck-chemicals.co.za/contact — Contact Merck Chemicals (Zambia Office)

• http://www.mobilis.co.za/ — Imports Pool Chemicals & Testing Supplies Into Africa

Sorry we cannot provide more assistance than we have, but we do hope one of the links above will point you in a useful direction.

For those interested in learning more about DPD and its uses, please check out an earlier posting entitled What is DPD?.

If you would like to purchase DPD from a retailer/distributor in the US, the following links will take you to a site where you can order DPD #1 and/or DPD #3 in packs of 100 and packs of 1,000.

While many companies have moved away from single parameter water testing meters and now produce meters that can test for a number of parameters instead of just one, Hanna recently released its new Hanna Checker HC Photometer for Free Chlorine which tests exclusively for free chlorine using EPA Approved DPD-1 as its reagent.

Specifications for the Hanna Checker HC Photometer for Free Chlorine:

• Detection Range: 0.00 to 2.50 ppm (mg/L)
• Resolution: 0.01 ppm (mg/L)
• Precision: ±0.03 ppm (mg/L) @ 25°C
• Power Source: (1) 1.5 Volt AAA Battery
• Light Source: 525 nm LED
• Sample Size: 10mL
• Applicable Testing Method: Adaptation of the EPA approved DPD method Standard Method 4500-ClG

Does the Hanna Checker HC Photometer for Free Chlorine use DPD?

We already answered this one, but yes, it does. The Hanna Checker HC Photometer for Free Chlorine uses an adaptation of the EPA approved DPD method Standard Method 4500-ClG. Given that the test uses a standard 10mL sample, we would guess that the meter can use any standard DPD reagents for a 10mL sample size.

Our opinion of the meter?

• Many of us here at Water Testing Blog have large hands with clumsy fingers so meters like this one that still use cuvettes, and GLASS cuvettes at that, kind of scare us. On top of that, most pool areas prohibit the use of glass in the pool area and many food processing facilities do as well.

• The meter appears to use pouches of powder which get ripped open prior to use… and we see people accidentally spilling the DPD powder and/or having trouble pouring the powder into the little cuvette — especially if testing outdoors in a breezy climate like one might find poolside.

• Having said all that, we DO, however, think that Hanna hit a nice price point w/ this meter; not too expensive and not too inexpensive.

• Hanna MISSED the mark w/ its pricing for the DPD-1 reagents. Each test will cost nearly $0.40 to run… when other testing methods use DPD-1 reagents (i.e. DPD tablets) that cost less than $0.10 per test.

Janet wrote in and asked…

I need to buy Dpd Tablets and I have not found a supplier nor a Manufacturer to buy from.

Kindly Link me with Dpd Tablets Manufacturers who can supply me.

We thank you very much, Janet, for your inquiry and suggest you take a look at the material below, as it will lead you to what you seek:

For those of you interested in learning more about DPD and its uses, please refer to an earlier posting entitled What id DPD?.

National Stock Number (NSN) for “Chlorine Test Tablet” — 6550012191061 and 6550014257957

We recently received a number of request from Water Testing Blog readers to post a list of popular water quality topics so that they could keep tabs on ‘hot topics’ more easily. Not wanting to disappoint, we have decided to do this on a semi-regular basis.

Below you will find the most popular Water Testing Blog entries for the month of July 2009:

• Free Chlorine and Total Chlorine: In this chlorine-related water quality blog posting we discussed why some chlorine testing products such as Pool Check Test Strips work exceptionally well for swimming pools and spas, but do not offer the correct chlorine detection levels required for drinking water.

• Free, Total & Combined Chlorine: In this chlorine-related water quality testing blog entry we dicussed the differences between free chlorine, total chlorine, and combine chlorine as well as methods to test for each one.

• Dirty Pool Water Can Make You Sick: The title pretty mucha says it all. Just as with drinking water, failing to test pool water can allow dangerous forms of bacteria to grow, flourish, and possibly make a person sick. Remember: 1 in 5 American Adults Admits to Peeing in the Pool. Yuck!

• www.pool-water-test-kits.com: In this posting we brought this pool water test kits to your attention. It’s a fast, easy way to find the pool/spa testing supplies you need to keep your water crystal clear, safe, and enjoyable.

• Free Water Hardness Test Strips: Here we pointed people to Morton Salt Company and Diamond Salt Company web sites where they could order free water hardness test strips.

• DPD Tablets for Chlorine Testing: We always stress the importance of accurate chlorine testing and in this post we provided links to a web site where readers could find replacement DPD tablets and replacement DPD powder for their chlorine/bromine test kits.

• Water Filters for Hikers & Campers: For all those who enjoy going for long walks in the woods, camping in the mountains, mountain biking, or just having clean, safe drinking water to drink when away from home, we provided links to personal water filtration devices and systems from the Katadyne Company.

• Hardness Grains per Gallon vs. Parts per Million: Once again, the name says it all. What more can we say about this posting dealing with water hardness measurement scales.

• Chlorine Filters for Garden Hoses: One would think people already know that the same chlorinated water they filter in their homes goes in their gardens, too, but apparently not… so we provided links to water filters for garden hoses.

• www.pool-water-testing.com: Here we simply brought a site dedicated to testing pool water to the spotlight. Not much more to say really… other than go test your pool often!

With temperatures soaring to record and near record highs all across the United States, it comes as no surprise to us that we have received numerous questions pertaining to the proper treatment of green swimming pool water, smelly swimming pool water… and some water that would make the average sewer worker vomit.

Therefore we have located yet another online source for Pool Water Testing and Pool Chemical Supplies. Below you will find quick links to various pool testing supplies, pool chemicals, pool shock treatments and other items such as automatic chemical feeders for swimming pools.

Just as with your drinking water, though, nothing beats a professional water test if you have reason to suspect that harmful bacteria or harmful levels of contaminants have entered your pool water.

With all the posts we’ve written about the importance of testing chlorine levels in drinking water, we seem to have forgotten that a lot of people have test kits already and simply need replacement dpd tablets. The links below will take you to a site where you can pick up replacement dpd tablets and DPD powder for the Taylor brand of water test kits for pools and spas.

Several membsers of the Water Testing Blog staff have spoken with members of the military, both currently enlisted and recently discharged, and found out that some soldiers do not have access to simple, efficient tools they can use to test potential drinking water while deployed in foregin countries.

In most cases they carry packets of sanitizing/disinfecting tablets which they can use to put into their canteens to kill off bacteria, but what about lead, arsenic, cyanide and other items which can EASILY render an entire unit inoperable and take them away from their assigned duties?

Thankfully US Army, Navy, Air Force, and Marine Corps medical units deployed around the globe now have the ability to make use of simple water quality test kits which give them the ability to read basic water quality parameters quickly and easily.

Arsenic in Water and Soil: Arsenic Quick^TM

Bacteria in Water: Bacteria Check

Chlorine Residual (Free): SenSafe^TM Free Chlorine Water Check

Chlorine Residual (Total): SenSafe^TM Total Chlorine Water Check

Cyanide in Water: Cyanide ReagentStrip^TM

DPD-1 and DPD-4 (Chlorine Testing): eXact DPD ReagentStrips^TM

Lead in Water: Lead in Water Test Kit

Multi Parameter (6 Parameters): Well Water Check

Multi Parameter (11 Parameters): Well Driller Standard Water Test Kit

Multi Parameter (13 Parameters): COMPLETE Water Test Kit

Multi Parameter (15 Parameters): Water Quality Test Kit

Most of us know how badly we feel after ‘a night on the town’ filled with margaritas, martinis, cocktails and body shots because of dehydration. Now try to imagine how our soldiers must feel after a few MONTHS in the desert wearing full combat gear.

Safe drinking water means safer soldiers.