Backflow devices reduce the chance of backflow flooding by preventing water flowing back up stormwater drainage paths and are one of the many ways Council helps to manage flooding in Brisbane.

IMO Dielectric unions have very limited benefit as the water within the pipe also conducts current, effectively defeating the “isolation” provided by the dielectric device. I see corroded nipples and fittings on and around water heaters all the time, regardless of whether dielectric isolated unions, couplings, connectors, etc. are used. Sometimes it’s caused by the copper flex connector with the integral isolator itself. Brass seems to have more universal compatibility, which is why I prefer to see brass nipples.

The corrosive product often fills the pipe diameter restricting the water flow and is often the source of rusty water. Our company does not promote the use of dielectric unions, because they do not effect the corrosion characteristics of the water heater. Due to our cathodic protection system, the juncture of the supply piping and the tank fitting is adequately protected by the cathodic protection system against corrosion without the buildups which occur in the dielectric union.

A dielectric union is designed to break the electrical contact between two dissimilar metals (to prevent galvanic corrosion). Most of the flexible copper connector hoses on water heaters have a plastic washer that acts as a dielectric union.

Visual inspection means just that. If you were unscrewing plumbing to check for missing parts , you, would have worse problems than lack of a proper dielectric union.

Any metal with a negative voltage when coupled with a metal with a more positive voltage potential will sacrifice (corrode) itself to protect the metal with more positive (noble) voltage. By placing a dielectric (insulating) fitting between two dissimilar metals, i.e. iron and copper, there is a break between the two. Therefore, in theory the iron will not corrode to protect the copper. In fact, the circuit is generally completed through the water, and depending on the water conductivity the iron will corrode at various rates.

I hear ya. All you can do is your best. Kinda like how in Illinois we observe the plumbing which is worded differently from the other systems that we are required to inspect. Everyone says it is because of the plumbing union , but my opinion is it also has to do with not unscrewing and turning shutoff’s. Plumbing is like that as we all know.

Dielectric unions may have been used many years ago and were installed with the thought to assist in reduction of corrosion that could develop at the piping connections. From time to time, this inquiry is brought to our attention stating the use of dielectric unions may be suggested required or should be, perhaps used.

Backflow devices can reduce the impact of flooding on areas impacted by backflow flooding but flooding can still occur from other sources depending on the location and conditions, or if the backflow levee is overtopped. Council advises residents and business to prepare for flooding to minimise the impact of flooding on their property.

The corroded, leaking dielectric union in the back was installed by a ‘licenced plumber’. I installed the copper tube/hose and fittings. I paid quite a bit more for the brass fittings, I guess that is why people like the galvanized steel ones (cheap).

The installation of unions on the inlet and the outlet waterlines and a shut-off valve in at least the cold inlet waterline is recommended, so the water heater may be easily disconnected for servicing.

When there is a concern with using dielectrics, a plastic lined nipple have the ends of the plastic fold over the end of the nipple which provided an excellent dielectric. The plastic engages the thread of the fitting a attached, whether it be the tank of the piping, thereby insulating the metal nipple from the water. This prevents corrosion on either part. These nipples have been certified as dielectrics in numerous areas of the United States.

Brisbane City Council acknowledges this Country and its Traditional Custodians. We pay our respects to the Elders, those who have passed into the Dreaming; those here today; those of tomorrow.

The way I read it is that Dyelectric fittings are not to be used becase the SAME type of pipe is required throughout. Correct?

I’ve attached and old tech bulleting from Rheem on the topic. I’m not sure if it’s still accessible on their site. Also note that the nipples on top of the water heater are supposed to be dielectric, but as far as I know you can’t tell visually once the plumbing is hooked up.

A variety of backflow devices have been installed across the city, each designed for the local drainage requirements. Some backflow devices self-close depending on hydraulic conditions. Council follows strict operating procedures to ensure the safe operation of these devices. Even though backflow devices have been installed, flooding may still occur from other flood sources. It is important to still prepare your home and family for flooding.

There are three referable dams located outside of the Brisbane local government area that are owned by Seqwater where spills may impact parts of the Brisbane local government area:

The required use of dielectric unions on our water heaters is not necessary. With this in mind, uniformity of piping material must be administered by the installer. What is meant by this is “the piping used in the system i.e.: copper, etc. must be the same throughout, to and from the water heater”. When different piping material connectors are used, corrosion can be immediate and will commence deterioration within days of installation Why is this? When two or more different metallic piping materials are used there can be some level of electrical current flow between the materials due to their different levels of electrical voltage potential. By uniformly using the same material to pipe the water heater, there is essentially no difference in electrical potential between the piping and the water heater tank. Therefore, dielectric fittings are not required when following the uniformity of piping material.

In extreme circumstances dams can also release water in an uncontrolled way. For referable dams, where downstream hazards for uncontrolled releases are significant, this process is managed through an Emergency Action Plan (EAP). Emergency Action Plans are managed through the dam owner.

The way I read it is that Dyelectric fittings are not to be used becase the SAME type of pipe is required throughout. Correct?

The theory that is in practice is described as follows: All metals when immersed in an electrolyte, such as water, have a voltage potential. This voltage potential varies from approximately +3.0 volts to a –3.0 volts. The relative activity of the metal is determined by voltage potential with those metals with negative voltages being most active and more likely to corrode. Magnesium, for instance, has a slightly negative voltage, approximately –2.0 volts, and will corrode very rapidly in certain waters. Iron has a voltage potential of –0.4 volts and rusts (corrodes) very rapidly when exposed to a moist atmosphere. Copper on the other hand has a voltage potential of +0.350

The map on this page shows the approximate location of Brisbane River backflow devices. These devices are located within the drainage network. For your safety, residents are advised not to enter the drainage network or waterways.

Ya I thought of that. Seems like the water heater would fail before serious dielectric corrosion. They only last 6 to 10 years here.

In some circumstances a dam spill may result in downstream flooding, which may cause localised flooding and localised road closures.

Probably better for the TX SOP to call out actual corrosion rather than all of the dielectric / non-dielectric scenarios or we’ll wind up with another SOP standard as silly and confusing to the public as the no AFCI defects in older homes.

Download a map of backflow device locations in Brisbane (Word - 1.2Mb). Council strongly advises residents not to enter the drainage network or waterways. To report an issue with a backflow device, please call the Council Contact Centre on 3403 8888.

Council has installed 66 backflow devices at 16 locations along the Brisbane River to help protect areas from backwater flooding. These river-based devices supplement existing devices located on Brisbane's creeks and coastal foreshore. These devices are part of a suite of tools Council employs to provide flood resilience to the community.

A backflow device may reduce the impact of backflow flooding from the Brisbane River. It does not mean your property is free from flooding. Depending on the location and conditions, flooding can still occur from multiple sources.

Future backflow device works will be considered in Council’s future drainage program, which is subject to Council’s annual budget and citywide priorities.

You can typically see part of the plastic washer/flange sticking out at the top of the fitting. This plastic fitting is frequently damaged when the fitting is tightened too much, causing a loss of the dielectric properties.

Seqwater Dam Release Notification Service provides residents with dam release notifications. Residents can select the dams they would like to receive notifications about.

I did not look at the picture on your post earlier. the nipple on the cold water connection in the photo is shipped by the water heater mfg that are delivered to plumbing suppliers and are used to prevent a galvanic reaction. Because the fittings add about $5.00 to the cost of the heater retail stores such as Home depot buy their heaters with out the nipples. Most of the problems occur when water heaters are installed by homeowners that do not know any better or by the plumber that works out of the back of his truck

A dielectric union is designed to break the electrical contact between two dissimilar metals (to prevent galvanic corrosion). Most of the flexible copper connector hoses on water heaters have a plastic washer that acts as a dielectric union.

The way I read it is that Dyelectric fittings are not to be used becase the SAME type of pipe is required throughout. Correct?

Some backflow devices self-close depending on hydraulic conditions. Council follows strict operating procedures to ensure safe operations of these devices.

Dams are important infrastructure used for water storage and flood mitigation. Dams are designed to mitigate flooding by temporarily detaining water during storm events and releasing that water in a controlled way to reduce downstream flooding. As the dam fills up and water reaches a set level it releases water. This is commonly referred to as a dam spill. All dams in the Brisbane Local Government Area are ungated, which means the water is not controlled through the operation of gates. These dams are designed to spill when the water level gets too high.

Some dams are deemed ‘referable dams’ under Queensland Government legislation. This is determined by an assessment that shows there is the potential risk of two or more people being impacted by downstream flooding due to dam failure.

Despite backflow devices being in place, flooding may still occur from other flood sources. Council advises residents and businesses to prepare for flooding to minimise the impact of flooding on their property.

TECHNICAL SERVICE DEPARTMENT Technical Service Bulletin 1-800-432-8373 Dielectric Technical Competence, Product Confidence Page 1 of 1 1221.doc Dielectric – an electricity, especially a substance with electrical conductivity less than a millionth (10 to the –6) of an MHO.