What is the recommended pressure for this expansion tank?

They come pressurized from the manufacturer with a required 4-6 psi.

What is the size of the male threaded fitting on the top? 3/8"?

Size? Mine is in storage so not sure . The thread is tapered for a tight fit. Check APEC web site. It likely is the 3/8". Appears to be less than 1/2" and for sure more than 1/4"

What is the recommended pressure for this expansion tank?

Label on my tank says 100 psi max. At one point, my tank was not putting out much water. I hooked up a pump which said there was about 20psi in the tank. I charged it to 95 and it works like it did when it was new.

I need replacement tank for my Ecowater ero335. Is this a comparable model. The company here says everything out there is plastic.

I do t know if this will fit your exact model. But it should. just make sure the intake/outtake valve is the same size as your current tank. This one is definitely not plastic and the water has tasted great.

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APEC Water Systems Tank-4 4 Gallon Residential Pre-Pressurized Reverse Osmosis Water Storage Tank

APEC Water Systems Tank-4 4 Gallon Residential Pre-Pressurized Reverse Osmosis Water Storage Tank

Product ID: 11011230

Details

Brand
APEC WATER
Capacity
4 Gallons
Included Components
TANK-4
Installation Type
Under Sink
Item Weight
0.9 Kilograms
Material
Stainless

💧4 Gallon capacity

⚙️Pre-pressurized for instant flow

🛡️Food-grade, certified bladder

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4826628₫

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Details

Brand
APEC WATER
Capacity
4 Gallons
Included Components
TANK-4

Description

💧 Elevate your RO system with premium pressure and pure performance!

SAFE DURABLE - Food-grade bladder and stainless steel connectors guarantee leak-free, odorless water storage.
VERSATILE INSTALLATION - Works efficiently in both vertical and horizontal positions with included tank stand.
MAXIMIZE YOUR HYDRATION - 4-gallon capacity holds up to 3.2 gallons of purified water, perfect for busy households.
CERTIFIED QUALITY ASSURANCE - Individually pressure-tested and CE approved for global safety and durability standards.
PRESSURE PERFECT PERFORMANCE - Pre-pressurized design ensures fast, consistent water flow without waiting.

The APEC Water Systems Tank-4 is a 4-gallon pre-pressurized reverse osmosis storage tank designed for residential use. Featuring a food-grade bladder and stainless steel construction, it delivers up to 3.2 gallons of purified water with fast flow rates. Certified for safety and durability, it supports versatile installation and ensures leak-free, odorless water storage, making it an industry-standard upgrade for RO systems.

Specifications

ASIN	B00LU28SHE
Brand	APEC WATER
Brand Name	APEC WATER
Capacity	4 Gallons
Color	White
Customer Reviews	4.6 out of 5 stars 3,258 Reviews
Global Trade Identification Number	00854961005310
Included Components	TANK-4
Item Dimensions L x W x H	11"L x 11"W x 14.5"H
Item Type Name	Reverse Osmosis Tank
Item Weight	0.9 Kilograms
Manufacturer	APEC Water Systems
Manufacturer Part Number	TANK-4
Material	Stainless Steel
Material Type	Stainless Steel
Model Number	TANK-4
Product Dimensions	11"L x 11"W x 14.5"H
Smart Home Compatibility	Not Smart Home Compatible
Specification Met	certified frustration-free
UPC	854961005310
Unit Count	1.0 Count

Reviews

C**R

3.12.2024

X**O

22.03.2026

A**R

6.12.2025

W**D

7.03.2026

A**R

12.12.2025

A**R

5.05.2024

U**E

7.02.2026

J**Z

24.03.2026

L**L

2.03.2026

7**R

19.10.2025

E**O

7.02.2024

J**O

4.07.2024

T**N

12.05.2024

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In stock

Sold byAmazon VietnamDelivered byDesertcartCustomer service byDesertcartReturns14 days · 30 with PRO

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