Wednesday, July 30, 2014

Pure Brewing Water Using Reverse Osmosis

I got really tired of running to the local food store hoping they had enough distilled water in stock for me to create my brewing water profile on brew day. So after a lot of research and comparison shopping I bought the SpectraPure CSP RO 90-AF reverse osmosis water filtration system and hooked it up. Initially after unpacking the unit I was a little intimidated by the colored water lines, voltage transformer, float valve, pressure gauge, shut off valve and installation instructions that came with the filter. But after about fifteen minutes of looking over the installation manual and parts I was confident it was going to be pretty easy to install in the location I had in mind.

SpectraPure CSP RO w/ Automatic Flush

Before I get into the details of the installation, use and maintenance of the reverse osmosis filter unit I'll include a little background information on the filtering process itself and provide you with some key features to look for when selecting a reverse osmosis filtration system. Reverse osmosis filters are more commonly referred to as RO filters, the process was first developed by the United States Navy to provide drinking water aboard ships. Reverse osmosis filtration is used in over 13,000 locations worldwide to desalinate water by removing salt and minerals from ocean, river and waste water sources and create pure drinking water to use for cooking, bathing and drinking.

In a brewery the local water supply line is connected to the sediment filter where particles as small as 0.5 micron are first filtered out. The water then passes through a 0.5 micron carbon block filter to remove bad taste and odor causing contaminants, including chlorine and chloramine, that can adversely impact the flavor of your beer. In the final stage the water is passed through a thin film composite RO membrane where minerals, salts, fluoride and nitrates are removed creating 95-98% pure water. The pure water produced by reverse osmosis provides a perfectly clean slate for building a brewing water profile to fit any style of beer you wish to brew.

Reverse Osmosis Common Terminology 

Sediment Filter reduces sand, silt, sediment and rust that affect the taste and appearance of the water.

Carbon Block filters reduce chlorine, taste and odor problems, particulate matter, and a wide range of contaminants of health concern -- cysts (cryptosporidium and giardia), VOCs (pesticides, herbicides, and chemicals), certain endocrine disrupters, Trihalomethanes (cancer-causing disinfection by-products), heavy metals (lead, mercury), turbidity, MTBE, Chloramines and asbestos

Thin Film Composite (TFC) membrane is made of a a synthetic material, and requires chlorine to be removed before the water enters the membrane. Chlorine will cause irreversible damage to a thin film membrane element and for this reason, carbon filters are used as pre-treatment in all residential reverse osmosis systems using TFC membranes. A Thin film membrane has a higher rejection rate (95-98%) and longer life than the CTA membrane.

Automatic Flush Control system (AFC) is used to periodically rinse the accumulated impurities and concentrated waste water from the surface of the RO membrane to help increase the life of the membrane. The AFC will flush the membrane for a short period at start-up, every hour during operation, and at shut-down.

Auto Shut Off valve stops the flow of water from the local water supply line when the output of RO water is stopped, this saves a lot of water.

Total Dissolved Solids (TDS) meter reads and displays the concentration of dissolved solids in a solution. Since dissolved ionized solids such as salts and minerals increase the conductivity of a solution, a TDS meter measures the conductivity of the solution and estimates the TDS from that. The digital TDS meter readout provides a way of telling how well the RO membrane is working, too high a reading indicates there are higher levels of dissolved solids in the RO water being produced.

Tri-color Pressure Gauge lets you know when the sediment and carbon block filters need to be changed. By reading the pressure differential between the local source supply line and the output of the filter media this gauge indicates when the filter cartridges need replacing.

Float Valve monitors the water level in an RO reservoir to automatically shut off the RO water feed to prevent overfilling. It works in the same way your auto sparge arm works in a mash lauter tun. Once the RO water feed has been shutoff the automatic flush control will run for about 30 seconds before shutting off the local water supply.

Fully Assembled And Working RO Filter
The assembly and installation of the RO filter unit was pretty easy once I read and understood the instructions that came with it. The unit is capable of producing 90 gallons of pure filtered water a day, that's nearly a gallon every 15 minutes, so it doesn't take very long to fill up a glass or bottle of water. One of the more important features of this unit is that it uses just two gallons of water to produce one gallon of pure RO water, when compared to other RO filters on the market that is substantially less waste water per gallon of purified water. The RO filter runs on typical residential water pressure, if your water pressure is below 40 psi you will need to buy a booster pump to increase the water pressure. The nominal specifications for the model I bought are 60 psi water pressure at 77F and 500 ppm TDS.

All the connections on the unit use 1/4 inch tubing and push connectors, so assembly is literally a snap. The unit was nearly fully assembled when it came out of the box, I did have to screw in a small 90 degree elbow on the left side to connect to the local water feed line, plug in the TDS meter's connection to the unit and the small 24 volt transformer that powers the unit. The two slotted mounting holes located on the back of the unit make hanging it to any flat surface a breeze. 

TDS Meter Mounted And Connected To The Filter
I set the TDS meter to monitor the output of the RO water, the readout numbers fell soon after the water was initially turned on, once the readout fell to it's lowest number the unit was ready to produce pure water. At first the readout was 026 and after an hour or two of running the reading fell to 010, it may fall even lower since I had just completed the installation yesterday I haven't had much time to use the unit.

Having The Right Connections

The 1/4 inch tubing that comes with the unit were color coded according to their intended usage. The local feed water line is colored black, the brine dump water line is yellow and the produced RO water line is colored blue. I'm not sure if this is an industry standard color code or just one that SpectraPure uses for it's line of RO filters but it was easy enough to understand when making the connections.

The black tubing that came with the filter had a hose connection on one end for connecting it directly to a hose bib if needed, which can make installing the unit a lot simpler. My sink already had a 1/4 inch tee adapter installed to the cold water line and after trimming the black line to length I used this connection to feed water to the filter. I still have about a three foot length of black tubing with the hose bib connection on one end if I ever need to use it.

The yellow brine waste water dump line has to be securely fastened to the sink so when the auto flush switches on the pressure doesn't force the line to move away from the sink's drain. During normal operation equal volumes of water flow from both the yellow waste line and the blue RO pure water line, the RO filter separates contaminants and routes the waste water to the yellow line while passing only pure water to the blue RO line.

The blue pure RO water line is used to supply contaminant free water and can be used with any faucet that has a 1/4 inch push connector on it. There are two type of faucets used with RO filters one is an air gap faucet the other a non-air gap faucet. In theory when using local city water if a water main break were to occur or the fire department opened a nearby fire hydrant the sudden loss of water pressure could suck contaminants back into the RO filters. Air gap faucets have three connections, one for the blue RO water line and the other two are used to connect the faucet in series with the yellow waste water line. In the event of a sudden drop in water pressure the waste water line, being open to the air in the drain, would prevent contaminants from being sucked back into the filters.

A 15-20% Increase In Pressure Indicates Filter Cartridges Need Changing
Using The Reverse Osmosis Filter

Once the RO filter has been securely mounted to a flat surface and the supply line and drain lines have been firmly connected its time to let water flow to the filter and begin producing pure reverse osmosis water. The unit in this article senses when the valve on the output is open and automatically begins a short membrane flush cycle to wash away any impurities that may be on the source side of the reverse osmosis membrane. If the output valve is shut the source water doesn't enter the filter and this feature saves lots of water as well as greatly extending the useful life of the RO membrane. Its important to know that the pressure in the yellow waste water line is very high during the auto flush cycle so you'll want to make sure that line is firmly held in place to prevent water splashing all over the place.

When it's time to fill a container with RO water simply open the output valve, located on the end of the blue RO water line, until the container is full. This starts the auto flush cycle that washes the membrane and this runs for about 30 seconds. Once the auto flush stops equal amounts of water will flow from the yellow waste line and the blue RO water output lines. A quick look at the TDS meter showed a reading of 0.10 after using the filter for a few days, so once the TDS reading has stopped decreasing in value its ok to collect the RO water you need. When the RO water output valve is closed the auto flush cycle will run again washing impurities off of the RO membrane before the filter shuts off the water flow.

Overall this unit is relatively inexpensive to use and maintenance is minimal thanks to the digital TDS meter that tells you how well the RO membrane is performing and the color coded filter pressure gauge that let's you know when the sediment and carbon block filter cartridges need replacing. Other than that a twice a year cleaning of the plastic filter housing with a mild mixture of bleach and soap, after removing the filter media, is pretty much all that's needed. I bought my unit to filter my brewing water before modifying it to suit a particular style of beer, but I also use the RO water for drinking, making coffee and iced tea. Needless to say the days of paying for then having to lug home heavy containers of drinking water and distilled water are now a thing of the past. The RO filter provides me and my family with more than enough fresh, clean, pure water whenever we need it.