Complete 500 Gallon per day

Watermaker DIY Kit

Not only will you save thousands, you will have an extensive understanding of the operation and function of your watermaker when complete 

In stock for immediate shipment

$3999.00 plus shipping FOB FL.

The only quality kit of its kind. Everything has been thought through and documented with detailed assembly instructions.

When complete, you will have produced our Nautilus 500, our most popular system that has an existing operation and maintenance manual.

If you have a basic level knowledge in using hand tools and following instructions, the DIY kit is a fun project that’s practical and saves you a substantial amount on installing your water system.

Highest quality parts proven in over 16 years of real world use.

The best value in the industry. You cannot source these parts anywhere else for less. Industry standard parts.

All 316 Stainless Steel Cat Pump and high pressure components.

Quick connecting John Guest parts for most low pressure piping and connectors.

Industrial grade electrical controls with low and high pressure switches

Control Box included with thermal overload relays for both pumps

 Easy to follow step by step instructions with clear photos and drawings for reference.

Simple design with automatic recurring fresh water flush standard.

Easy to operate and maintain.

Some comments from our DIY customers

“How great it was to see you again yesterday. I was again impressed with how you really care about your product.  I will sing your praises to the boating world and certainly my yacht club friends”.

 “The remote button will work great on my boat.  Gett’n old ain’t no fun and crawling down in the engine room to turn on the watermaker every time I need water; my wife takes a shower everyday regardless of my complaining, is not something I look forward to do”.

 “I really do appreciate doing business with you. A very satisfied customer”.

 “We have the new watermaker together and are getting ready to install it per your instructions, which are pretty good by the way.  You guys didn’t miss a glue joint”.

“Anyway, looking forward to using your system this summer and many years to come”.

 “Hello, I am beginning to assemble the Watermaker, so far your instructions are quite good and the provided pictures are a real help”.

DIY guy

A Brief Overlook of the Detailed Instructions:


Each individual component selected to make up this kit is the result of over thirty years of experience in the industry and every single component has been carefully selected to provide the best possible performance.  We recognize the importance of producing pure water and our intent is to provide the most robust, well-designed system available to allow you to do so.

Basic skills required:

We have written these instructions with the intent to ensure that you successfully complete the assembly of this equipment.   If you have had experience with any basic mechanical repair and can read and follow instructions you will be able to successfully assemble and install  your watermaker.

Tools required:

You will need basic hand tools for the installation-

  • Screwdrivers – Slotted and Philips small medium and large
  • Combination wrenches from 7/16” to ¾”
  • Socket wrenches 7/16” to ¾”
  • Adjustable wrenches small and medium
  • Pipe wrench – medium
  • Allen Key – 3/16”
  • Wire strippers for 10AWG to 22AWG
  • Crimpers for electrical connectors

Supplies required:

You will need a few supplies and items to assemble the equipment, many of which you may have on hand, if not these are available from Sea-R.O.

  • Teflon Tape – standard white ½”
  • Teflon Tape – for stainless steel ½”
  • Silicone lubricant – Dow #7 or Dow #111
  • Rectorseal Tru-Blu thread sealant
  • Neverseize
  • Thread lock
  • Electric Tape

Sub-Assemblies Included:

  1. Prefilter Assembly
  2. Fresh Water Flush
  3. Low Pressure Pump
  4. High Pressure Pump
  5. PVA Pressure Vessel Assembly
  6. Electrical Control Box
  7. and installation materials



Assembly & Installation

The system is comprised of 6 sub-assemblies which are designed to be installed individually on the boat or machinery space and then plumbed and wired together.  This type of installation allows the best use of existing space and provides for easier service access in the future.  It is important to lay out the components of each sub-assembly before beginning to verify that you have all necessary parts available to continue the assembly/installation.  We highly recommend tackling the installation in manageable stages and completing each sub-assembly one at a time to prevent the possibility of mixing up parts

This manual has been divided into sections that address each sub-assembly, each section includes an itemized list and pictures of each sub-assembly kit for cross referencing.

The subassemblies are:

  1. Feed Pump – The feed pump delivers the water to the rest of the system. The pump is a centrifugal type which works in conjunction with the high pressure pump and prefiltration to maintain an adequate feed pressure to the high pressure pump as the filters become loaded with sediment, plankton, etc.
  2. Prefilter Assembly – The Prefilter assembly filters all of the feed water before entering the high pressure pump and membrane. By filtering the feed water to 5 microns, the filters protect the high pressure pump seals and internal components and prevent physical fouling of the membrane.
  3. Fresh Water Flush Assembly- The Fresh Water Flush Assembly utilizes the pressurized fresh water supply from the boat or home to purge the RO system of sea water at the end of every running cycle. This greatly extends the life of the membrane and all system components and maintains the best water quality that the system produces. When sea water sits idle too long, it will cause biofouling and potential odor and by flushing the system, we prevent this from occurring.
  4. High Pressure Pump Assembly- This is the heart of the system and is where the high pressure (normally 800 psi) is produced to make the reverse osmosis process possible. The pump uses water lubricated ceramic plungers to pressurize the water and has an oil filled crankcase for long life and quiet and smooth operation.
  5. Pressure Vessel Assembly – This is where the actual reverse osmosis process occurs. About 75% of the water pumped into the system is discharged back to the sea and this “brine” carries away the salts. The fresh water is squeezed through the membrane and exits out through the product flow meter into the storage tank. The membrane is housed inside of the pressure vessel which contains the high pressure required for the process.
  6. Electrical Control Box Assembly – The Electrical Control Assembly is where the system is operated from to start and stop and contains the high voltage contactors and safety devices such as thermal overloads and pressure switch circuits that protect the operator and system components from environmental conditions and operator error.
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