What is Turbidity?

by Brian Campbell

Editor’s Note: Brian Campbell is the founder of WaterFilterGuru.com.  The article below is a good introductory overview of what water treatment professionals mean when they talk about “turbidity.”

If you’re researching the common drinking water contaminants, you may have heard of turbidity. Turbidity isn’t actually a contaminant itself, which can make it difficult to understand exactly what you’re dealing with.

This short guide will equip you with the information you need to know about turbidity in drinking water: what it is, how it’s measured, and its effects.

What is Turbidity of Water?

The turbidity of water is a measurement of how clear or cloudy it is. The cloudier the water, the higher its turbidity.

To get a little more scientific, turbidity measures a liquid’s “relative clarity” – or the amount of light that refracts off materials in a liquid sample. The more light is refracted within a sample of water, the higher the level of turbidity.

There are a number of materials that can cause turbidity, including silt, inorganic and organic matter, clay, algae, and some microscopic organisms.

How is Turbidity Measured?

Turbidity is measured in Nephelometric Turbidity Units, known as NTU for short. Turbidity may also be measured in Formazin Nephelometric Units, or FNU.

You can measure turbidity using a turbidity meter or sensor, which will use scatter-detection methods to quickly detect the levels of total suspended solids (TSS) in water. TSS – referring to waterborne particles that are larger than 2 microns – are the common culprits behind turbidity.

Editor’s Note:  To clarify, here’s an explanation  by the same author to help distinguish between Total Suspended Solids and Turbidity:

Turbidity and suspended solids are often used interchangeably, which can make it difficult to understand the difference between the two. However, they are not quite the same thing. Turbidity refers to water’s transparency and the more suspended solids water contains, the less transparent it will be. In short, turbidity is a measurement of how well light can pass through water, while TSS is a quantitative measurement of suspended particles in water. 

What Are the Most Common Causes of High Turbidity?

The most common causes of high turbidity are phytoplankton, erosion, urban runoff, wastewater discharge, algae and sediment disruption. More detail on each of these causes is listed below.

Phytoplankton

Phytoplankton are a type of marine algae, which are microscopic in size but are capable of turning water brownish-red when present in high concentrations. These organisms often float or “drift” in water, and can survive in both fresh and saltwater environments.

Erosion

Water affected by erosion can also have high levels of turbidity. Imagine a river flowing through an area of loose dirt. When this dirt is worn away, it can seep into water. The consistent force of a flowing river can also erode tougher materials, like rock. This can increase the sediment level in water, often resulting in cloudiness.

Urban Runoff

Urban runoff is rainwater (or melted snow) runoff in urban areas, which can be responsible for pollution or contamination of water sources like private wells, lakes, and rivers.

When water runs through agricultural or industrial sites, building surface materials, and even some impermeable paved surfaces, it may collect sediment that increases the turbidity of whichever water source it ends up in.

Wastewater Discharge

When wastewater discharge isn’t treated properly, it may carry pathogens, suspended solids, and other contaminants into a body of water, increasing its turbidity. This water usually comes from pipes from factories and plants that treat wastewater.

While the EPA has produced guidelines on how to treat wastewater before discharging it, many water sources are not correctly treated before being discharged.

Algae

Algae are a group of organisms that live in saltwater and freshwater bodies. You can find algae in a variety of sizes and appearances, and sometimes these organisms are too small to be seen by the human eye.

Algae take nutrients from the water, improving oxygen levels. But when algae die, organic matter is released into the water, increasing turbidity. Some algae are rooted to the surface of the ground, while others float on the surface of water.

Sediment Disruption

Similar to erosion, sediment disruption occurs when water picks up a body of sediment and carries it to a new location, increasing the turbidity of specific areas, such as the pool of water beneath a waterfall. In rivers, this sediment disruption can affect water flow and alter the depth of the water.

What Are the Effects of High Turbidity?

The biggest problem with high turbidity is that it affects the aesthetic quality of a water source. Not only can this negatively impact tourism and recreation, but it can also affect marine or aquatic life by reducing oxygen and food supplies.

From a water treatment perspective, it is more expensive to treat water with high turbidity as it must be more thoroughly filtered to remove sediment of all different sizes.

Drinking water that has high turbidity levels may be dangerous, depending on the cause of the water’s turbidity. For instance, water that contains certain suspended solids like algae and bacteria may make you sick to drink. Other common causes of turbidity, like sand and dirt, might not make you sick, but this sediment could have an effect on the infrastructure of your home’s pipes, plumbing and water-based appliances.

Turbidity vs Total Suspended Solids (TSS)

Turbidity and total suspended solids are linked – but they’re not the same thing. As we know, turbidity is a measurement of how transparent water is. Suspended solids, on the other hand, are the contaminants that are largely responsible for turbidity in water.

In short, the higher the levels of total suspended solids in water, the greater the level of refractions of light from these materials, and the higher the turbidity.

Pure Water Gazette Fair Use Statement

More about turbidity from the Gazette’s website.

Pura O Rings

Getting the right o ring for a Pura UV unit isn’t always simple. The chart below is designed to help.

All o rings listed can be found here.

There is one exception. There is an intermediate BB unit built between Fall 2009 and Jan. 2012. It uses a unique o ring: OR017.

Pure Water Products  Simple Cartridge-Style Iron Filter

An ideal solution for moderate iron, moderate water-use applications

Standard tank-style backwashing iron filters are normally used for iron removal from well water. They are very effective, but they are large and they require a drain connection, electricity, and a significant amount of water for regeneration. They eventually need media replacement and replacement or rebuilding of control heads. In other words, although they can solve the significant problems caused by iron and manganese in well water, they are fairly expensive to purchase and they can be an ongoing expense and a maintenance chore.

Our cartridge filter for iron is for small amounts of iron (generally less than 3 parts per million). It can help with manganese as well, but is not a good treatment for hydrogen sulfide odors. This easy-to-install system is recommended for applications where pH is 7.0 or higher and service flow rates are usually 4 or 5 gpm or less. Multiple units, of course, can be installed in parallel for higher service flow rates.

The cartridge used for this free-flowing filter is the advanced Pentek radial flow iron removal filter with iron oxide media. See this chart for approximate gallon capacities.

The housing is the old faithful 20″ Big Blue from Pentek with 1″ or 3/4″ ports. A heavy stainless mounting bracket, screws, and filter wrench are included.

Basic unit comes with housing, bracket with screws, filter wrench and a Pentek iron removal cartridge.

Suggested Applications

Multiple iron filters can be installed in parallel to accommodate homes that need higher flow rates. The illustration shows a sediment filter followed by two iron units in parallel. This filter array can comfortably treat iron at residential service flow rates of seven or eight gallons per minute. Moderate use homes with up to four people can use a single unit. With more than 4, a double unit as shown above is needed.

Please call for pricing.

Please call 888 382 3814 for more information or to order.

See more details about the cartridge used in this unit. 

Links to Products for City Water Treatment

Products that Deal with Water Hardness

The pages below contain information about the three leading types of hardness treatment for city water.

Conventional Water Softeners

TAC, Template Assisted Crystallization. (ScaleNet, also known as OneFlow)

Siliphos

Whole House Filtration Units

Compact Whole House Filters (Cartridge Style).  Multi-Filter Versions of Compact Whole House Filters.  (See links to other items in this series at the bottom of the article.)

Tank Style Backwashing Filters for Chlorine or Chloramines (See Carbon and Catalytic Carbon units.)

Drinking Water Units

Reverse Osmosis Units  (Black and White)

Simple Undersink Filters — No faucet needed. Filtered water is dispensed through cold water side of the standard sink faucet.

Undersink Filters  (Black and White Series)  — Filters with their own faucet for filtered water.

More information?  Please call 888 382 3814.

Putting Ourselves in Our Place: What If We All Sat in the Ocean at Once?

Editor’s Note:  Probably this is something you’ve wondered about. If everyone on earth decided to go swimming in the ocean at the same time, would there be room for all of us? And would the water spill out of the world’s oceans causing devastating flooding?  To put our minds at ease, here’s the answer from the Curious Kids section of at The Conversation website. 

You can think about the oceans as a gigantic bathtub. More than 70% of the Earth’s surface is ocean, giving this bathtub an area of about 140 million square miles. To figure out how much the water will rise, we need to know the volume of people sitting in it and divide it by this ocean area.

Currently, there are almost 8 billion people on Earth. Human beings come in all sizes, from tiny babies to large adults. Let’s assume the average size is 5 feet tall – a bit bigger than a child – with an average volume of 10 cubic feet. Only half of each person’s body would be submerged when they sit down, so only 5 cubic feet adds to the water level. With 8 billion people total, you can calculate 5 x 8 billion which gives a whopping 40 billion cubic feet that would be added to the oceans.

But remember, this volume would be spread over the vast area of the oceans. Using the same bathtub math as before, we divide the 40 billion cubic feet of volume over the 140 million square miles of ocean.

The answer? The total rise in sea level would be about 0.00012 of an inch, or less than 1/1000th of an inch. If everyone completely submerged themselves, this would double the answer to 0.00024 inches, which is still only about the width of a human hair.

It turns out the oceans are enormous – and humans are just a drop in the bucket.

Source: The Conversation.

Pure Water Gazette Fair Use Statement

Converting your Black and White Countertop RO Unit (Style A) to a Standard 3-stage Black and White Reverse Osmosis Unit

The Finished Product

These instructions apply only to Pure Water Products’ standard style A Countertop Reverse Osmosis Unit.  The parts and instructions do not apply to other products.

In addition to the Black and White Style A RO Unit,  here’s what you’ll need:

Our Conversion Kit.  Part Number RP105.  The Kit costs around $198 and includes everything you will need.  Parts can be ordered from our main website using the part numbers of the individual parts.

1  ta005 Storage Tank.

1 jg011 1/4″ tee.

1  jg014 Tank Valve.

1  rc300 Auto Shutoff Valve.

1  rc200 ASO-Membrane Clip

2  rc001 JG Check Valves

1  rc100 Drain Saddle Kit

1  iv100 or iv103 Inlet Kit

1  lf700 Pro-Flo Faucet

5  tb001 Five feet of 1/4″ tubing.

Here’s how you do it

Converting your Black and White Countertop RO to Undersink

1. Install the faucet and inlet kits. When conversion is complete and you install the unit, you will plug the inlet tube into the black (left) housing and the faucet tube into the right (white).

2. Mount the shutoff valve in its clip on top of the RO membrane with the IN/OUT side of the valve facing the capped end of the membrane housing (the end that has only one tube).

3. Remove the tube from the fitting on the membrane cap and install it into the IN port of the shutoff valve.  Run a new tube from the OUT port to the recently vacated fitting in the membrane housing cap.

4. On the other end of the membrane, remove the tube from the Permeate fitting (the one that isn’t the drain) and replace it with a short tube that connects it to the nearest TANK port of the shutoff valve.  Insert a check valve into the new tube between the membrane and the shutoff valve with the arrow pointing toward the shutoff valve.

5. Loop the tube you removed from the Permeate port of the membrane back and insert it into the remaining empty port of the shutoff valve.  (The other end remains connected to the back port of the white postfilter housing.)  At any convenient place in this tube, insert the tee to connect the tank to the unit.

6. Install the shutoff valve onto the top of the storage tank, then use a single tube to connect the tank valve to the tee that you installed in step 5.

7. Install the drain saddle following instructions in the kit and connect the existing RO drain tube to the fitting in the drain saddle.  Install the remaining check valve between the drain line flow restrictor and the drain saddle with the arrow pointing toward the drain saddle.

Refer to the picture at the top of this article as a model, and don’t hesitate to call or email us if you hit a snag.

Pure Water Products

888 382 3814

pwp@purewaterproducts.com

Boil Water Orders Are Increasing

What This Means to Residential Water Users

by Gene Franks

“Boil water” alerts are issued by water suppliers when the safety of the water they deliver is in question. The standard instruction is that water should be brought to a rolling boil for at least one minute (longer at higher altitudes) to kill waterborne pathogens.

Formerly, government agencies tracked boil water alerts in the US as public information, but as the number of alerts has increased dramatically in recent times record keeping is no longer done. In the absence of such information, Dr. Kelly Reynolds of the University of Arizona recently used a Google News search to identify boil water alerts across the US for a two-week period in August 2013. Dr. Reynolds found 29 alerts during the period.

Alerts are issued for a variety of reasons–bad weather, especially flooding, a break in a water main, low system pressure, finding of fecal coliform by testing, system leaks, system maintenance, detection of E. coli or cryptosporidium by routing testing, and general elevated bacteria counts—are the most common.

As pipes and pumps age, and as power outages and incidents of challenging weather become more frequent, it is certain that boil water alerts will become more common.

The boil water strategy for assuring micro-biologically safe water is at best a risky one. We have been conditioned to rely on the safety of our water systems to provide potable water, but this perception of safety is changing. Each time a pipe ruptures or pressure in the pipe goes down, microbes are drawn into the delivery system. A blanket “boil water” warning, even if given on time and received by all concerned, is a haphazard way to assure safety. Studies have shown that both reception of the alert and compliance with its recommendations are far below 100%.

It is certain that we have gone past the time of complete trust in the water delivery system to provide pathogen-free water. Just as more and more people are now relying on home treatment devices to provide chemical-free and more aesthetically pleasing water for drinking, cooking, and bathing, it is logical that “final barrier” devices to assure that water is free of bacteria, viruses and protozoa are becoming more common for city residents.

Fortunately, modern water treatment has developed many alternatives–from very tight filters for drinking water to whole house treatments like ultraviolet. These are certain to become prominent fixtures in US homes. As Dr. Reynolds says, “The inherent, unpredictable nature of the distribution system and the quality maintenance of the distributed water add credence to the need for routine POU [point of use] treatment.”

Reference: Water Conditioning and Purification, Sept., 2013.

Start-up of Katalox Light Backwashing Filter

The following instructions are adapted from the media manufacturer’s start-up instructions.

1. Open the new bag of Katalox-Light media and put into the pressure vessel.  (Use a standard softener funnel, and be sure to cover the top of the riser tube to keep Katalox from going into the tube.)

2. With water off, or the filter in bypass, put the control valve into “backwash” position. Fill up the pressure vessel slowly with fresh water from bottom to the top with the control valve in backwash mode.  (The control valve can be unplugged to keep it in backwash as long as needed.)

3. Turn on the water completely and backwash the media for a minimum of 20 minutes.

 
4. After the backwash is complete perform a rapid rinse for for at least 5 minutes.