Question 1

What is Reverse Osmosis?

Accepted Answer

Osmosis is when water passes through a membrane (a sheetlike boundary) and other materials cannot pass through or can only pass through in lower amounts. Osmosis happens in all living things naturally, because all life needs water. When water is separated by a membrane, pressure is created by the amount of foreign materials in the water. The pressure will push water from the side of the membrane with less foreign materials until there is a balance between water and foreign particles is equal on both sides.  With some clever science and engineering, osmosis can be made to work for us. We just add pressure, from your home’s water pressure, to the side with more foreign material. The extra pressure can stop or reverse this flow. This means that water will now only flow away from the foreign material. This is Reverse Osmosis.

Question 2

How Does Reverse Osmosis Work?

Accepted Answer

In Reverse Osmosis we apply extra pressure to the water to push it through thousands and thousands of membrane layers. The extra pressure stops foreign materials from drawing water to them. The result is these foreign materials are left behind and the only thing that can come through the membrane layers is pure water.  The Reverse Osmosis Membrane is only one stage of our RO Systems; it’s the 4th stage. The 1st stage is a Sediment filter which helps filter things like dirt, sand, dust, and rust. The 2nd and 3rd stages are Carbon Filters which filter things like chlorine, volatile organic chemicals, and odor-causing compounds.  These early stages help extend the life of the Reverse Osmosis Membrane by taking care of many larger coarse contaminants which could damage it. But they do not deal well with Total Dissolved Solids (TDS) which are the most difficult to remove. Ninety-eight percent of TDS are removed by the RO Membrane as well as other difficult contaminants like lead, arsenic, chromium, and radium. The Membrane is where most of the purification takes place.  The 5th stage is a granular-activated carbon filter which does a final pass on your water right before you drink it. This last stage is focused on removing any possible taste or odor in your water. It’s the combination of these stages that’s helped countless customers have water purer than bottled water straight from their faucet.  Express Water Reverse Osmosis Filters  To learn more about the Reverse Osmosis products offered by Express Water, please visit our Reverse Osmosis Systems page.

Question 3

Drinking Water Contaminants

Accepted Answer

Total Dissolved Solids (TDS): What are they?  Total Dissolved Solids (TDS) are all organic and inorganic contaminants that have been dissolved into water. These contaminants are gathered from everything water comes into contact with before it finds its way to you. Common elements of TDS are Iron, Sulfate, and Chloride.  Contaminants: What contaminants are reduced by Reverse Osmosis?  Reverse Osmosis reduces a huge variety of Total Dissolved Solids in water.  We have charted out some common TDS contaminants and what percent of reduction you can generally expect below.  These numbers are based on tap water tested in Southern California. The exact results may vary depending on the water quality in your area.  Contaminate comparison chart: Reverse Osmosis vs Pitchers and Faucet Mounted Filters.  Does Reverse Osmosis remove Parasites, Bacteria, Cysts, and Cryptosporidium?  NSF's rating for reduction of Giardia Cysts and Cryptosporidium is 1 micron, and the Thin Film Membrane (TFM) filters down to 1/10,000th of a micron. That is 10,000 times smaller than these parasites. These contaminants are too large to pass through the TFM membrane. Although, a health claim cannot be made because of intangibles such as regular maintenance.

Question 4

What happens to filtered impurities?

Accepted Answer

Impurities removed by the RO System are washed down the drain. Unlike other filters, the Reverse Osmosis membrane is self-cleaning. As water flows through the RO membrane, it is divided into two streams. One stream is pushed through the membrane by your water pressure. The second stream flows to the drain carrying dissolved pollutants, rejected salts, and contaminates. This means very little debris accumulates on your membrane allowing it to last for about a full year of use.

Question 5

Express Water Reverse Osmosis Systems

Accepted Answer

Water Pressure: How important is water pressure to an RO System?  Water pressure pushes water through the Reverse Osmosis membrane for purification and flushes the rejected solids away. Low water pressure will result in reduced production and premature fouling of the RO membrane. The ideal pressure for operating an RO system is 60 PSI. Pressure below 40 PSI is considered insufficient, and should be increased using a booster pump, which we offer and can guide you through installing. If your PSI is too high we offer Pressure Regulators to reduce your pressure to acceptable levels. Let us walk you through these options: call us at 1-800-992-8876 or visit expresswater.com  Iron: Will iron hurt an RO System?  Iron will plug an RO membrane, as the membrane is not able to flush iron out. Trace amounts of iron (up to 2 PPM) can be removed by a water softener. If the water contains 1 PPM or less, there is no need for concern as the membrane will not be significantly affected.  Note: This refers to clear water iron, not red iron. You can tell the difference because clear water iron leaves no visible signs, whereas red iron leaves a reddish brown discoloration in toilet bowls, tanks, sinks, and tubs. If red iron is present, steps to remove the iron will have to be taken.  Water Differences and Dissolved Solids: How is RO Water different from tap water? How will I know the RO System is removing Dissolved Solids from my tap water?  The biggest difference from tap water and evidence the system is functioning is in the taste and clarity of the water produced. Cooking, coffee, drinks, and juices made with RO water will taste better. Ice cubes made with RO water are harder, clearer, and last much longer.  Ice Test: If you take two similar glasses and put ice cubes made with RO water in one and the same number of ice cubes made from tap water in the other, you will notice that it takes longer for the RO ice cubes to melt. When you melt tap water ice cubes you usually see sediments on the bottom of a glass. This doesn’t happen with RO water.  Conductivity Test: Another way of determining the amount of dissolved solids removed from tap water is by using a conductivity meter. This meter measures the conductivity which dissolved solids create in water. The meter will tell you the parts per million of Total Dissolved Solids (TDS). Express Water offers a water sample kit for the testing of a customer's water to determine how the RO Membrane is working. It can also help to determine when to replace the membrane.  Lifespan: How long does the system last? How long does the tank last?  With proper maintenance and average water quality an RO System should last 5-10 years. The water storage tank usually lasts 3-5 years before we recommend replacing it.  My Home: How do I know this system will work in my home?  The first thing you can do is make sure your installation location has enough room for the system (most people install under their kitchen sink). The Reverse Osmosis Unit is 15.75” x 16.25” x 5.25” and the Water Storage Tank is 11” x 16” x 11”.  The next thing you should do is make sure your home’s water pressure will work with the system. The system works with a minimum water pressure of 40 PSI and a maximum of 80 PSI. If your PSI is too high you can purchase a Pressure Regulator to reduce your pressure to acceptable levels. If your PSI is too low you may need a Booster Pump to aid your system.  If you’re not sure if this system will work in your home: let one of our technicians help you figure it out; call us at 1-800-992-8876 - 10am-5pm (Pacific Time) Monday-Friday.  System Life: How long does the system last? How long does the tank last?  With proper maintenance and average water quality an RO System should last 5-10 years. The water storage tank usually lasts 3-5 years before we recommend replacing it.  Tank Capacity: How much water can the Water Storage Tank hold?  The maximum capacity of the standard RO tank is 3.2 gallons. However, the typical tank reaches 2-2.5 gallons. Your Water Storage Tank’s capacity depends on your incoming water pressure. Lower water pressure means the tank will hold less water.

Question 6

Water Softeners & Reverse Osmosis Systems

Accepted Answer

Water Softeners: Does a water softener treat my drinking water?  Water softeners do not treat water for drinking purposes. A water softener is good for the home's plumbing and water-related appliances, but does little to improve the taste or quality of your drinking water. A water softener reduces hardness (calcium and magnesium) in tap water by adding salts and is usually installed at the point-of-entry of water to the house. However, it does not treat for countless other contaminants which can affect the taste and purity of your water.  Water Softeners: Will a water softener harm a Reverse Osmosis System?  Water softeners actually help extend the life of the your RO System. Water softeners remove calcium and magnesium by adding sodium to water. Calcium and magnesium are two of the hardest minerals for an RO Membrane to remove. Sodium (added to the water by the softener) is much easier on the membrane. Ninety-eight percent of the sodium water softeners add are removed by the membrane.  Water Softeners: Will an RO System soften water?  Water is softened through the Reverse Osmosis process. However, hard water (above 7 grains of hardness) will shorten the life of the RO Membrane. The harder the water, the shorter the life of the Membrane. We recommend using a water softener if your area has hard water. The softener should take effect before the water enters the RO System.  Water Softeners: How do water softeners work with the RO System?  If your area has hard water we recommend running your water through a water softener before it enters the RO System. A water softener helps extend the life of the RO System. Water Softeners remove calcium and magnesium by adding sodium to water. Calcium and magnesium are two of the hardest minerals for an RO Membrane to remove. Sodium (added to the water by the softener) is much easier on the membrane. 98% of the sodium water softeners add are removed by the membrane.  If you don’t have a water softener the Reverse Osmosis process will soften water. However. hard water (above 7 grains of hardness) will shorten the life of the RO Membrane. The harder the water, the shorter the lifespan. We recommend using a water softener if your area has hard water. The softener should take effect before the water enters the RO System.

Question 7

Do RO Systems send water down the drain?

Accepted Answer

Some of the water that goes into an RO System does go to the drain. This drained water is carrying away filtered contaminants. The drained particles are too small to be caught by filters. They can only be safely disposed of by being flushed down the drain. The system only uses as much water as needed to dispose of impurities. The exact amount of water used changes with the quality of the water going into the system.

Question 8

What is the discharge rate?

Accepted Answer

The typical discharge range is three gallons for every one gallon produced.

Question 9

What is the ratio of wastewater to pure water produced by an Express Water RO System?

Accepted Answer

Your water pressure, incoming water quality, and water temperature will affect your RO System’s discharge rate.

Question 10

Can wastewater be saved and used?

Accepted Answer

Yes. Even if your wastewater goes down the drain most is recycled for golf courses and artificial lakes. The drain water is higher in TDS concentration than tap water, but it can be used to water your lawn or garden. Never consume your wastewater.

Question 11

Water Filter Maintenance & Care

Accepted Answer

Filter Changes: Is it necessary to change the filters every six months?  It is recommended to change the 1st, 2nd, and 3rd stage filters every six months. By changing the pre-filters (1st, 2nd, 3rd) on a regular six month basis you will avoid dirt and chemicals that will plug the RO membrane. Your local water conditions can affect how often you need to change your filters.  Flow Restrictor: Is it necessary to change the Flow Restrictor when I change the RO Membrane?  No, you don’t have to change your flow restrictor with our RO System. Express Water uses a newer “inline flow restrictor”. Unlike other varieties this flow restrictor can be cleaned, so there is no need to replace it when you replace your RO Membrane.

Question 12

Water Filter Upgrades

Accepted Answer

Filter Upgrades: Can I add additional filters to my current system?  Each system is fully upgradeable. Alkaline Filters help add minerals and extra oxygen to your water. Deionization Filters help remove even trace minerals making water fit for aquariums, humidifiers, and other machines. Ultraviolet Sterilizers help eliminate microbial life from water where this is a concern. Check the Upgrades and Accessories section at expresswater.com for more information.  Refrigerator and Ice Makers: Can I connect this system to a refrigerator or icemaker?  The RO System can be connected to a refrigerator or icemaker. But you may need an Express Water Refrigerator Kit to do so. In some cases, your situation may require a separate tank or Delivery Pump depending on how far away your refrigerator is from the unit. Contact Express Water and we’ll help you find your solution.  System Upgrades: Can I change my 50 GPD (Gallons Per Day) system to 100 GDP? If so, how?  To upgrade your system from 50 GDP to 100 GDP you will need different parts (such as the RO Membrane and Flow Restrictor). Contact Express Water and we will help you arrange your upgrade.  Email: support@expresswater.com  Call: (800) 992-8876  10am-5pm PST Monday-Friday

Question 13

Water Filter User Manuals & Installation FAQs

Accepted Answer

Water Filter User Manuals  CLICK HERE to access our product user manuals.  Mounting Locations: Does the RO System have to be under the kitchen sink?  No, the RO System can be mounted in a cabinet to either side of the kitchen sink or even mounted remotely in a garage or basement.  Dimensions: What are the dimensions of an Express Water RO System?  The module part of the RO system measures: Height: 15.75" Width: 16.25" Depth: 5.25". The storage tank measures: Diameter: 11" Height: 16”.  Line Length Maximum: How far can a line run from the RO System?  Your line can run approximately 20-25 feet with ¼" Poly Tubing. For runs longer use 3/8" Poly Tubing, and a ⅜” to ¼” adapter. Never use copper tubing with an RO System, even when running to an ice maker.  Copper Tubing: Why not use copper tubing with an RO System?  Water from an RO system has almost no contaminants. So, it is known as "hungry water." Hungry water can leach the minerals out of the copper tubing and may cause a metallic taste in water or ice cubes over time. The copper tubing can develop pinhole leaks as well.  Install Locations: Can I install this system in the basement? Can I install somewhere other than under my sink?  The RO System can be installed in other locations like a basement. But, the further away from the faucet the system is installed the more water pressure the system needs. You may need to purchase a Delivery Pump for a far away install location. Contact Express Water and we’ll help you find your solution.

Question 14

Ordering and Website Support

Accepted Answer

Shipping: When will I get my package?  For shipping in the US we send all orders within 48 hours of receiving them. Generally any order should arrive within one week. Orders are shipped via Fedex Ground and usually reach their destination within 2-5 days (depending on where you live). If you have special requirements for your shipping contact us:  Email: support@expresswater.com  Call: (800) 992-8876  10am-5pm PST Monday-Friday  Returns: How do returns work?  If your product is found to be defective, within 30 days of purchase, we will help arrange for the product to be sent back. After 30 days the product is subject to the warranty offered with the product. Take a look at our Returns page if you need to start a return.  Warranty: How does the warranty work?  All Express Water Reverse Osmosis Systems are covered by a one-year warranty which covers parts and manufacturing defects. For more details take a look at our warranty.  Canceling an Order: How do I cancel an order?  If your item has not been shipped yet you can cancel your order (most items are shipped within two days of placing your order). Just contact support and they will help to cancel your order. If your item has already been picked up for shipment it cannot be canceled and you will have to return the item for a refund.  Technical Difficulties: I’m having trouble using the site or getting through checkout, what should I do?  If for any reason you are having trouble with the website, checkout, or any other technical issue let our support help you out.  Email: support@expresswater.com  Call: (800) 992-8876  10am-5pm PST Monday-Friday

ROT600 Replacement Filters

Model 6 - 1st Stage Replacement Prefilter

Model 6 - 2nd Stage Replacement RO Membrane

High-Capacity Filtration for Reliable, Long-Term Water Purification

How the ROT600 Filtration Process Works

Installation & Filter Change Videos

Frequently Asked Questions

🔹 How often should I replace my ROT600 filters?

🔹 What contaminants do these filters remove?

Which system is right for you?