Today’s inquiry comes to us from a woman serving her country in the United States Navy. ‘Ronda’ had a question about the DPD products she had seen on our web site.

“Do your DPD Chlorine tabs work in Hach equipment?”

Good afternoon, Ronda, and thank you for this inquiry. When weighing the different DPD options (tablets, powders, reagentstrips, etc.) make sure you note the sample size that each test method will work in. As a general rule most devices that use DPD as a reagent will have 10 mL sample sizes, but we have also seen devices that use 15 mL sample sizes, 7 mL sample sizes and 20 mL sample sizes.

Check your machine’s manual to find out what sample size it takes. In order to remain compliant with whatever drinking water directives you follow you will need to match up the sample size w/ the correct reagent amount.

Specifically, though, you asked about the DPD tablets for chlorine testing that we have shown on our site and as far as we know all of the DPD products we have shown on our site work for 10 mL samples — except for the eXact Micro DPD products which work in smaller samples.

Two 10-mL Tablets/Strips/Powders for a 20-mL Sample?

While in theory that would work, definitely check your approved testing method to see if it expressly forbids that sort of thing and/or if it specifically calls for a brand or type of chlorine reagent delivery method. In the past we have seen where testing protocols have gotten so granular that they call out not only the type of DPD used, but also the brand of the test meter and DPD used for chlorine testing.

No matter how many ‘new’ and/or ‘innovative’ methods scientists devise to make water safe for drinking, we believe a certain faction in society will still put its trust in the sanitizing effects of free chlorine. This also means we believe a need for chlorine testing will always exist.

As an immediate example of this need, a Water Testing Blog reader named John recently asked,

“Hi, I am installing a 5000 litre water tank which i intend to add chlorine to and need an inexpensive free chlorine meter could you advise me on what to purchase as this is a new venture for me. Regards, John M.”

Thank you, John, for your question. We will begin by saying that you should immediately narrow your search by eliminating any water quality testing meters not using a form of DPD-1 as the reagent for free chlorine testing.

While ORP meters do offer a good bit of utility, their readings do not directly monitor just free chlorine content of water and a great number of water quality purists still feel that traditional DPD chemistry provides the best means of determining a sample’s relative safety — based solely upon the sample’s chlorine concentration, of course.

With that said, DPD comes in several forms: Liquids, Powders, Tablets, and ReagentStrips.

To answer John’s question directly, though, at this time Water Testing Blog recommends the eXact Micro 7+ Water Testing Meter as the ‘preferred’ choice for an inexpensive meter for testing chlorine concentrations — and 20+ other water quality parameters if users desire.

Yeah, yeah, we know… we almost ALWAYS suggest the eXact Micro 7+ Meter. This time, however, since John did ask specifically about an inexpensive chlorine testing meter, the fact that Filter Water Superstore (FilterWater.Com) has the basic meter kit on sale makes it even MORE of a good choice.

Pricing verified on 2/1/2012 and the basic test kit includes…

• 1 eXact® Micro 7+ Meter
• 1 bottle of eXact® Strip Micro DPD-1 (25 tests)
• 1 bottle of eXact® Strip Micro DPD-3 (25 tests)
• 1 bottle of eXact® Strip Micro pH (25 tests)
• 1 bottle of eXact® Strip Micro Total Alkalinity (25 tests)
• 1 bottle of eXact® Strip Micro Calcium Hardness (25 tests)
• 1 bottle of eXact® Strip Micro Copper (25 tests)
• 1 Mixing Cap
• 1 Cell Cleaning Brush
• 1 Instruction Booklet
• Plastic Carrying Case
• Four AAA Batteries to power the meter

What sort of detection range does the meter have? So glad you asked!

Naturally you will want to, or you should want to, know about the cost of replacement reagent(strips) for the meter. Since John asked about chlorine testing, below you will find links to, and pricing for, replacement DPD-1 and DPD-3 ReagentStrips — currently available at several online locations such as FiltersFast.Com and FilterWater.Com.

So if you find yourself in the market for a chlorine testing meter that uses an EPA Compliant testing method AND offers additional testing capabilities, definitely take a look at the line of eXact Micro 7+ Meters.

Recently we received a request for a quote on 5,000 DPD #1 Tablets for chlorine (or possibly another oxidizer) level testing. We’d like to remind remind everyone that although we link to a number of water quality products, Water Testing Blog does not stock or sell any products.

The party asking about DPD #1 Tablets sought to import them into a foreign country so we suggested they contact companies on the following page:

( http://www.alibaba.com/showroom/dpd-tablets.html )

… so they could attempt to save a few bucks (or whatever currency they use) on shipping.

Now having said that, when it comes to DPD #1 we believe anyone thinking about using DPD tablets should at least consider using DPD-1 ReagentStrips in their place. ReagentStrips dissolve faster and easier than tablets (especially in hard or cold water) and contain no filler materials that could interfere with photometric optics.

As far as performance, the manufacturer of DPD-1 ReagentStrips, Industrial Test Systems, Inc., had an independent laboratory conduct a blind water sampling study using DPD ReagentStrips, Tablets and Powder Pillows. In the end the ReagentStrips tested as good, and in some cases better, than other DPD reagent delivery methods.

Every once in a while we get requests from foreign countries asking for pricing and availability of specific products.

Unfortunately we do not know a whole lot about the International market and what products exist in countries outside of the United States and Canada, but we generally assume that interested parties can acquire the same stuff we can, just at a higher cost due to import taxes and shipping fees.

Having said that, though, today’s international inquiry comes from ‘Zahid Afzal’ in Pakistan who asked who wants to know, specifically, about places to purchase a product called the Hanna Checker HC Photometer for Free Chlorine

Dear Sir/Madam,

Can you please give us the price for the “Hanna Checker HC Photometer for Free Chlorine” for our project in the Flood affected areas of Pakistan.

Regards,

Zahid Afzal

Thanks for the inquiry, Zahid. We really don’t know all that much about the “Hanna Checker HC Photometer for Free Chlorine“… except that a swimming pool supply company ( In the Swim ) began carrying this product at some point last Summer.

Having said that, do you really want to use a pool water testing device to test drinking water?

Granted we have said over and over again that doing ANY testing of drinking water in an area recently affected by flood waters makes more sense than performing no testing at all, but we would suggest looking into other meters… or possibly even into simpler testing methods that do not rely upon chemical reagents (i.e. DPD powders, DPD tablets, DPD reagentstrips, DPD liquids, etc.)

OK, so maybe not ‘new’, but having spoken with the manufacturers of this product, we can safely say that a whole lot of people who could really use this product do not know of its existence.

For years people conducting tests for certain varieties of oxidizers (Free Chlorine, Chlorine Dioxide, Bromine, Iodine, and Permanganate) have relied upon DPD-1 tablets, DPD-1 powders and DPD-1 liquids to help them obtain accurate, repeatable results.

Now, however, an easier method of adding DPD-1 reagent to test samples has become available on FilterWater.Com, an online retailer of water quality testing and water quality improvement products.

Why consider switching to DPD-1 ReagentStrips?

• The United States Environmental Protection Agency has deemed the DPD-1 ReagentStrip test procedure equivalent to USEPA method 330.5 for wastewater when used in conjunction with a Palintest Chlorometer 1000 equivalent meter (i.e. the eXact Chlorine Photometer).

• The United States Environmental Protection Agency has deemed the DPD-1 ReagentStrip test procedure equivalent to USEPA method Standard Method 4500-Cl G for drinking water when used in conjunction with a Palintest Chlorometer 1000 equivalent meter (i.e. the eXact Chlorine Photometer).

• eXact DPD-1 Reagentstrips deliver a precise dose of DPD-1 reagent into a 10 mL sample without the need to count drops (DPD-1 liquids).

• Working in the field with DPD-1 Reagentstrips becomes much easier since testing personnel will not have to worry about small or large gusts of wind blowing away their reagent as they attempt to add it to a sample (DPD-1 powders).

• Due to the ‘dehydrated nature’ of DPD-1 Reagentstrips, they will dispense rapidly and easily into hard and cold water without the need for laborious, time consuming tablet crushing (DPD-1 tablets).

• As long a the test instrument (i.e. meter or test kit) uses as standard 10 mL sample size, an eXact DPD-1 Reagentstrip will provide consistent test results regardles of who made the test kit/meter.

If you use DPD-1 on a regular basis we think you owe it to yourself to give eXact DPD-1 ReagentStrips a try.

Note: For those who know a thing or two about DPD, you may find yourself wondering why we didn’t compare the DPD-1 ReagentStrip to an old school method of reagent delivery called ampuoles which involves breaking glass tips off into test samples. Ahem… Breaking of glass in order to perform testing. Need we say anything more about ampuoles?

Most people looking to test their drinking water for chlorine want to know the concentration of free chlorine, also called the free chlorine residual, in their drinking water. Basically speaking, free chlorine (hypochlorous acid) acts as an effective sanitizing and disinfecting agent in lower concentrations but can cause serious harm and damage to organic material (i.e. human skin, hair, cells, etc.) in higher concentrations.

The US Environmental Protection Agency has set the Maximum Contaminant Level (MCL) for free chlorine at 4.0 parts per million, also known as milligrams per liter (mg/L).

The most commonly used test for free chlorine residual uses a reagent called DPD (what is DPD?). More specifically, it requires DPD-1 and DPD-1 comes in several different forms: liquid, powder, tablet and reagentstrip form.

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

Looking for a versatile, lightweight, waterproof water quality testing meter? Need an EPA Compliant testing meter for chlorine testing?

Introducing a new photometer using a patented method and technologies that offer faster, safer, easier, and more precise water testing.
The eXact Micro 7+ offers seven modes which provide direct read capabilities for Total Alkalinity, Bromine, Calcium Hardness, Free Chlorine, Total Chlorine, Copper, Ozone, Permanganate, pH, and % Transmission – which allows for testing of an additional 17 parameters.

The eXact Micro 7+ can measure a total of up to 26 parameters and provides EPA Compliant testing method for both Free & Total Chlorine when used with DPD chemistry.

In need of replacement reagentstrip bottles for your eXact Micro 7+ Water Quality Testing Meter?

Update — Looking for an easier way to use DPD-1 with your existing chlorine test kit or meter? If it uses as 10 mL sample, then you definitely want to check out DPD-1 ReagentStrips for free chlorine. They mix into solution much quicker, easier and cleanly than DPD powders and DPD tablets and have a much longer shelf life than DPD liquids.

No one in their right mind would argue that testing water for drinking, use in a pool, watering crops, etc. has to happen. One might, however, argue that using test strips and liquid test kits which require the user to match colors can lead to approximations and assumptions regarding critical water parameters such as pH, chlorine/bromine/sanitizer levels, alkalinity, total hardness, heavy metals, etc.

We all know what assumptions can lead to: Making an a## out of you and me.

No one wants to get sick from dirty or polluted water so when accuracy matters most, you may want to put down the test strips and liquid test kits and opt for a verstile water testing meter such as the eXact Micro 7+ which tests for NINE critical water parameters using direct read measurements and an additional TWENTY-SEVEN other important water parameters with the use of a conversion chart.

Features of the eXact Micro 7+ Water Testing Meter:

• Tests for 36 parameters in total

• Nine direct read parameters — Total Alkalinity, Bromine, Calcium Hardness, Free Chlorine, Total Chlorine, Copper, Ozone, Permanganate, and pH

• Twenty-Seven parameters using a conversion chart: Ammonia, Chloride (as NaCl), Chlorine Dioxide (DPD-1), Chromium Hexavalent, Cyanuric Acid, Fluoride, Hydrazine, Hydrogen Peroxide (Low, Mid and High Range), Iodine (DPD-1), Iron (Fe+2), Total Iron (Fe+2/Fe+3), LR Total Hardness (as CaCO3), Magnesium, Manganese, Nitrate (as NO3), Nitrite (as NO2), pH (Acid and Alkali), Potassium, Protein (as BSA), Sulfate, Sulfide, and Turbidity

• USEPA Compliant meter for Free & Total Chlorine — 0.01 ppm (mg/L) precision

• Built-in, permanent cell — no loose glass or plastic cells to lose

• Easy fill testing — Simply fill or dip meter into water

• Automatic countdown timer for accurate timing of testing

• 140 test memory — saves 20 tests per menu item

• Incorporates eXact® Strip technology — safe & reliable reagent dispersion

• No-slip grip housing — ideal for wet testing conditions

• Lightweight — weighs only 6 ounces w/ batteries installed

• Waterproof — IP-67 Rated and meter will float if dropped into water

• Easy-to-read LCD display — no color matching required

• Environmentally friendly — recyclable parts & uses 60% less reagents than 10mL sample tests

• Proprietary optics — allows for accurate testing without cap

• CE certification

Interested in learning how this device works? Check out the image below as it takes you through the steps of how to test w/ the eXact Micro 7+ Water Testing Meter.

Several members 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 foreign 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.