What size thread is a RV water inlet?
I remember my first big trip in our new-to-us RV. We pulled into a beautiful campsite by a lake, excited to get set up and relax. I grabbed the white drinking water hose, screwed it onto the campground spigot, and then walked it over to the RV. As I tightened the hose to the plastic city water inlet, I heard a sickening crack. Water immediately started spraying everywhere, soaking the side of the RV and me. The cheap, sun-baked plastic flange had completely failed.
That moment is a perfect mix of frustration and panic. Your relaxing vacation has immediately turned into an emergency repair job. You're worried about water getting into the walls of your RV, causing rot and damage you can't see. You try to patch it with whatever you have on hand, but you can't trust the connection. It puts a damper on the entire trip, all because of one small, low-quality part.
The standard thread size for an RV city water inlet is a 3/4" GHT (Garden Hose Thread) on the outside where you connect your drinking water hose. The internal connection, which attaches to your RV's plumbing pipes, is typically a 1/2" NPT (National Pipe Thread). Knowing these two standard sizes is the key to a quick and stress-free replacement.
Understanding these specifications is the first step, but a reliable connection involves more than just thread size. Let's look at why these essential components fail and how you can ensure yours is dependable for years to come.
Why is my RV water inlet leaking?
You've connected your hose and tightened it properly, but you still see that annoying, persistent drip. Or worse, a fine spray is coming from the body of the inlet itself. You check the hose connection again, but it's not the source of the leak.
This is a problem that sends many RVers into a state of anxiety. Water is the enemy of an RV's structure. A constant leak, no matter how small, can lead to delamination, wood rot, and mold growth inside the walls. You can't just ignore it, but you're also worried that it's a complex plumbing problem that will be expensive to fix at a dealership.
The good news is that the problem is almost always the city water inlet flange itself, which is a simple and inexpensive part to replace. Leaks are typically caused by one of three things: the cheap plastic housing has become brittle from sun exposure and has a hairline crack, the internal check valve has failed, or the simple hose washer inside has dried out and no longer seals properly.
Your RV water inlet is likely leaking due to a cracked plastic housing, a worn-out hose washer, or a malfunctioning internal check valve (also known as a backflow preventer). UV damage and freezing temperatures are the most common culprits for causing the plastic components to fail.
Fixing this problem is one of the easiest and most important DIY tasks for any RV owner.
Dive Deeper: Pinpointing the Source of the Leak
Before you replace anything, it's helpful to understand exactly where the failure is. This knowledge will give you confidence in your repair.
Common Failure Points
| Component | Symptom | Common Cause | Solution |
|---|---|---|---|
| Hose Washer | A slow drip from the hose connection point. | The small rubber washer is old, cracked, or missing. | Easiest fix: Replace the washer. |
| Plastic Housing | Water leaking or spraying from the body of the flange. | UV exposure, over-tightening, or frost damage. | Best fix: Replace the entire inlet flange. |
| Check Valve | Water flows back out of the inlet when the hose is disconnected. | A worn-out spring or seal inside the valve. | Best fix: Replace the entire inlet flange. |
The Problem with Factory-Installed Plastic
Manufacturers often use plastic inlets to save on costs. While functional, this plastic is highly susceptible to degradation from the sun's UV rays, which makes it brittle over time. A little too much force when tightening a hose or a single winter freeze can be enough to cause a catastrophic crack. Upgrading to a solid brass inlet like the Boltigen flange is a permanent solution to this common problem.
What is a backflow preventer and why do I need one?
You hook up your hose to the city water connection, and you naturally assume that water only flows in one direction: into your RV. It feels like a simple, one-way street. You don't often think about what would happen if the water flowed the other way.
This lack of awareness can lead to a dangerous situation. Imagine the water pressure at the campground suddenly drops. This can create a siphon effect, potentially pulling water from your RV's plumbing system—including water from your onboard tank which may not be as fresh—back into the campground's main water supply. This is a serious health risk that could contaminate the water for everyone at the park.
A backflow preventer, usually in the form of a simple check valve, is a critical safety device built directly into your city water inlet. It's a one-way gate that allows pressurized water from the hose to flow into your RV but automatically snaps shut if the pressure drops, preventing any water from flowing back out. This protects both your RV's plumbing system and the public water supply.
A backflow preventer in your RV water inlet is a one-way valve that allows water to enter from the city connection but prevents water from your RV's plumbing from flowing back out. This is a crucial safety feature that protects the campground's water supply from potential contamination.
This small, unseen part plays a huge role in responsible RVing.
Dive Deeper: The Importance of a Secure Water System
How a Check Valve Works
The mechanism is beautifully simple. A small spring holds a plunger or diaphragm against a seal, keeping the valve closed. When you connect a pressurized hose, the incoming water pressure is strong enough to push the plunger open, allowing water to flow into your RV. If that incoming pressure is lost, the spring instantly pushes the plunger closed again, creating a secure seal.
Why Lead-Free Brass Matters
Your city water inlet is the gateway for all the water you use for drinking, cooking, and showering. It is essential that this component does not leach harmful substances into your water.
| Material | Pros | Cons |
|---|---|---|
| Plastic | Inexpensive | Brittle, susceptible to UV damage and cracks. |
| Standard Brass | Strong, durable | Can contain small amounts of lead. |
| Boltigen Lead-Free Brass | Extremely durable, resists corrosion | Certified safe for drinking water systems (NSF). |
Choosing a certified lead-free brass inlet like the Boltigen model ensures your water system is not only durable but also safe for you and your family.
How do I replace my RV city water inlet?
You've identified the leak, and you have your new, high-quality brass inlet ready to go. Now it's time for the installation. If you're not an experienced plumber, the thought of cutting into your RV's plumbing system can be intimidating. You want to be sure you can do the job correctly without creating new leaks.
Hesitation is normal, but this is one of the most straightforward DIY jobs you can do on your RV. The process is simple and requires only a few basic tools. The key is to work carefully and ensure you create good, watertight seals on both the plumbing and the exterior wall.
Replacing your RV city water inlet is a simple process. First, turn off the water supply and disconnect the hose. Then, remove the screws holding the old flange to the RV wall and disconnect the water line from the back. Finally, apply fresh sealant, connect the new inlet to the water line, and screw the new flange into place.
Follow these steps for a perfect, leak-free installation.
Dive Deeper: A Simple Step-by-Step Guide
Tools and Materials Needed:
- New Boltigen RV City Water Inlet
- Screwdriver or screw gun
- Adjustable wrench or channel-lock pliers
- RV sealant tape or butyl tape
- Plastic scraper or putty knife
The Installation Process
| Step | Action | Pro Tip |
|---|---|---|
| 1. Disconnect | Turn off the city water and your RV's water pump. Disconnect the water hose. | Open a faucet inside your RV to relieve any remaining pressure in the lines. |
| 2. Remove Old Inlet | Unscrew the two or three mounting screws on the outside flange. Carefully pull it away from the wall. | Use a plastic scraper to gently break the old sealant bead. Be careful not to scratch your RV's siding. |
| 3. Disconnect Plumbing | Reach behind the flange and unscrew the PEX water line from the 1/2" NPT connection. | You may need pliers or a wrench for this. Have a small towel ready for any drips. |
| 4. Prepare Surface | Clean all the old sealant from the RV's exterior wall to ensure a clean surface. | Isopropyl alcohol works great for removing any sticky residue. |
| 5. Install New Inlet | Apply a bead of sealant or a layer of butyl tape to the back of the new Boltigen flange. Connect the PEX line to the back of the inlet, then press the flange into place and secure it with the new screws. | Do not over-tighten the screws. You want them snug enough to compress the sealant evenly. |
| 6. Test | Connect your water hose, turn on the spigot, and carefully check for leaks both outside and inside the RV. | Clean up any excess sealant that squeezed out for a professional finish. |
The Last Water Inlet You'll Need to Buy
Don't let a cheap, broken part ruin another camping trip. By upgrading to the Boltigen Solid Brass RV City Water Inlet, you're not just fixing a leak—you're installing peace of mind. You get a durable, lead-free, and reliable connection that will stand up to the elements and the rigors of the road for years to come.
Upgrade your RV with a component you can trust. Shop now on our official website: Boltigen Brass RV City Water Inlet Flange
Or get it shipped fast from our Amazon store: Boltigen Brass RV City Water Inlet on Amazon