Quick Answer
A water-treatment skid may deliver the required treated-water flow while consuming more raw water than the project expected.
To verify actual data center water recovery, teams need a complete measurement boundary covering raw-water inlet, treated-water outlet, backwash, reject, rinse, recycle, sludge and drain flows.
The accumulated values must also cover the same reporting period. Without this alignment, treatment capacity may be visible while actual water use remains difficult to explain.
Why This Matters Now
On July 28, 2026, Xylem raised its full-year profit outlook and indicated that AI infrastructure expansion was strengthening demand for water-treatment equipment.
This development shows that AI-related water demand is extending beyond cooling-system headlines into treatment skids, water-recovery systems and supporting infrastructure.
As more treatment equipment enters data center projects, project teams need to confirm more than rated treatment capacity. They also need field flow data showing how much raw water becomes product water and how much leaves through backwash, reject and discharge streams.
Treatment Capacity Is Not the Same as Water Recovery
Treatment capacity describes how much water a system is designed to process or produce under specified conditions.
Water recovery describes the share of incoming raw water that becomes usable treated water during a defined operating period.
A skid can meet its treated-water outlet target while using more raw water than expected because of:
Filter backwash
Membrane reject or concentrate
Rinse and regeneration water
Chemical preparation
Recycle streams
Sludge discharge
Drain connections
Startup and shutdown discharge
If these side flows are not measured, the system may appear to have sufficient capacity while the actual water yield remains unclear.
Design Recovery Versus Field-Verified Water Recovery
A design recovery rate describes the intended process under defined design conditions.
A field-verified recovery rate must come from synchronized accumulated flow values across the complete water boundary.
This distinction matters because actual operation may include:
Changing raw-water quality
Partial-load production
Additional backwash cycles
Longer rinse periods
Startup flushing
Frequent regeneration
Internal recycle
Maintenance drainage
Changes in storage-tank volume
Design values remain useful for planning, but they cannot replace field totals when teams need to explain actual water consumption.
Define the Complete Data Center Water Recovery Boundary
A clear water boundary should identify every stream entering, leaving or returning to the treatment process.
The main measurement points normally include:
Raw-water inlet
Treated-water or product-water outlet
Filter backwash
Membrane reject or concentrate
Rinse and regeneration water
Recycle or recovery stream
Chemical preparation water
Sludge discharge
Drain discharge
Startup and shutdown discharge
Each point should have a defined purpose.
For example, the raw-water inlet may represent all new water entering the treatment area, while the product-water outlet may represent water delivered to the cooling system or storage tank.
Recycle flow should be identified separately so that internally circulated water is not counted as new raw-water intake.
Backwash Flow Is Usually a Short Peak
Filter backwash is often inactive for long periods and then operates at a relatively high flow for a short cycle.
This creates a different measurement duty from the main treated-water line.
Before selecting the measurement point, engineers should confirm:
Minimum backwash flow
Peak backwash flow
Typical cycle duration
Number of cycles per day
Whether the pipe remains full
Whether flow reverses
Required total volume per cycle
Required PLC signal
Reset and totalization logic
For water-recovery calculations, accumulated backwash volume is usually more useful than one instantaneous flow reading.
A flow range based only on normal treatment operation may not cover the backwash peak correctly.
Reject Flow Directly Affects Recovery Calculations
Membrane reject or concentrate is one of the most important side streams in a water-recovery calculation.
The reject line explains part of the difference between raw-water inlet and treated-water outlet totals.
Application review should include:
Liquid conductivity
Solids or suspended material
Minimum and maximum flow
Operating pressure
Process temperature
Whether the pipe remains full
Continuous or intermittent discharge
Changes during startup
Changes during shutdown
Discharge to drain, tank or further treatment
A suitable flowmeter cannot compensate for a pipe that is only partially filled. The hydraulic condition and installation position must be reviewed before selection.
Rinse and Regeneration Water Can Distort Daily Totals
Rinse and regeneration cycles may operate independently from the main treatment process.
A regeneration event may begin during one reporting period and finish during another. The treatment skid, cooling system and facility-management platform may also reset accumulated totals at different times.
Engineers should confirm:
Which treatment train used the water
When the cycle started and ended
Which reporting period contains the volume
Whether the accumulated value resets automatically
Whether operators can reset the total manually
Whether the value remains stored after power interruption
Without a consistent reporting period, normal operating events can appear as unexplained water losses.
Chemical Lines Need Their Own Flow-Range Review
Chemical preparation and dosing lines often operate at much lower flows than the main water lines.
A flowmeter selected for the main treatment line should not automatically be applied to a small chemical line.
The review should include:
Minimum chemical flow
Normal chemical flow
Maximum chemical flow
Chemical concentration
Conductivity
Process temperature
Material compatibility
Presence of bubbles
Pulsating flow
Required output signal
The expected minimum flow must remain within the effective measuring range of the selected instrument.
Recycle Flow Must Be Counted Correctly
Recycle or recovery streams may pass through part of the treatment system more than once.
If recycle flow is counted as new raw-water intake, the reported treated volume can be overstated. If it is excluded completely, teams may lose visibility into internal circulation.
The control strategy should clearly define whether each accumulated value represents:
New water entering the facility
Water entering the treatment skid
Internal recycle
Water returned from another process
Final product water
Water sent to discharge
This definition should be shared across the skid builder, water EPC, facility team and cooling-system integrator.
Sludge and Drain Flows Can Add Up
Drain and sludge connections are sometimes treated as minor utility lines.
However, repeated small discharges can create a meaningful accumulated volume over a day, week or month.
These flows may include:
Sampling discharge
Maintenance drainage
Startup flushing
Cleaning water
Sludge removal
Tank overflow
Emergency discharge
Shutdown drainage
Where water-recovery reporting is important, these streams should be included in the boundary review rather than treated as unexplained losses.
Align Totalization Across Treatment and Cooling Systems
A complete set of flowmeters can still produce an inconsistent water balance when accumulated totals use different time periods.
For example:
The treatment skid may reset totals every shift.
The cooling system may report by calendar day.
Backwash volume may be stored by cycle.
Reject flow may be reported continuously.
The facility platform may use a different time zone.
Before comparing totals, engineers should confirm:
Start and end time for each accumulated value
Time zone used by every controller
PLC reset logic
Manual reset permissions
Power-loss data retention
Engineering units
Batch and continuous-flow separation
Tank-level changes during the reporting period
The same measurement period allows different teams to work from the same water balance.
Confirm Minimum, Normal and Peak Flow
Treatment systems rarely operate at one fixed flow.
Each measurement point should include:
Minimum operating flow
Normal operating flow
Maximum continuous flow
Short-duration peak flow
Startup flow
Shutdown discharge
Partial-load flow
Standby circulation
Future expansion flow
A flowmeter sized mainly around maximum treatment capacity may provide limited visibility at low operating flow.
A flowmeter sized only around normal production may not cover a short backwash or drain peak.
Where one line has several very different duties, teams should consider whether separate measurement points provide a clearer result.
Confirm Full-Pipe Conditions Before Selection
Full-pipe condition is important for many water and wastewater measurement points.
Potential problem locations include:
Gravity drains
Downward discharge pipes
Pipe high points
Open-tank outlets
Reject lines with changing backpressure
Pipes that empty between cycles
Lines installed before a free discharge
Pipes where air can collect
The installation position should be reviewed before the product is selected.
Where full-pipe operation cannot be maintained, the measurement point may need to be relocated or the piping arrangement adjusted.
Which Approved Velomac Products May Be Relevant?
Electromagnetic Flowmeter
An Electromagnetic Flowmeter may be considered for conductive liquids such as raw water, treated water, backwash water, reject water and selected wastewater streams.
The application review should confirm:
Liquid conductivity
Full-pipe condition
Pipe size
Minimum and maximum flow
Short-duration peak flow
Solids content
Liner and electrode compatibility
Installation direction
Available straight pipe
Grounding conditions
Required accumulated total
PLC or DCS output
The instrument should not be selected only because the medium is described as water. Conductivity, flow range, installation position and pipe condition still need to be checked.
Ultrasonic Flowmeter
An Ultrasonic Flowmeter may be considered for selected existing large-diameter water lines where cutting the pipe is difficult.
This can be useful for some retrofit projects, subject to confirmation of:
Pipe material
Pipe outside diameter
Wall thickness
Internal lining
Pipe condition
Fluid condition
Full-pipe operation
Available straight run
Sensor mounting access
Required signal output
Required accumulated total
Existing pipe details should be verified at the site rather than taken only from old drawings.
What Engineers Should Prepare Before Flowmeter Selection
Prepare the following information for each measurement point:
Stream name
Measurement purpose
Raw water, product water, backwash, reject, rinse, recycle or drain duty
Liquid composition
Conductivity
Solids content
Pipe size
Pipe schedule
Pipe material
Internal lining
Minimum flow
Normal flow
Maximum flow
Short-duration peak flow
Pressure
Temperature
Continuous or intermittent operation
Full-pipe condition
Flow direction
Available installation length
Upstream and downstream disturbances
Required accumulated total
PLC, DCS, pulse or analog output
Shutdown availability
Expected future capacity
Each stream should be reviewed independently. One common specification may not suit the main water line, backwash line, reject line and drain line equally.
What Velomac Usually Reviews
For a data center water-treatment application, Velomac can review the complete measurement point before selection.
The manufacturer-direct application review can cover:
Medium and conductivity
Pipe size and material
Minimum and peak flow
Continuous and intermittent operation
Full-pipe condition
Installation position
Available straight pipe
Retrofit restrictions
Totalization period
PLC or DCS output
Relevant Electromagnetic Flowmeter or Ultrasonic Flowmeter configuration
This review helps water EPCs, skid builders, facility engineers and system integrators clarify the measurement boundary before ordering.
Practical Checklist
Define the raw-water inlet boundary.
Define the treated-water outlet boundary.
List every backwash, reject, rinse, recycle, sludge and drain stream.
Separate continuous flow from intermittent flow.
Record minimum, normal and peak flow.
Confirm backwash volume per cycle.
Confirm whether every pipe remains full.
Check liquid conductivity.
Verify pipe material, wall thickness and lining.
Include storage-tank changes in the water balance.
Align totalization periods across all systems.
Confirm reset and data-retention logic.
Confirm PLC, DCS, pulse and analog output requirements.
Identify lines that cannot be cut during retrofit.
Include startup and shutdown discharge.
Review future treatment-capacity changes.
Calculate recovery from field totals rather than design values alone.
Common Questions
Can raw-water inlet and treated-water outlet totals show recovery?
They can provide a basic recovery ratio when both totals cover the same period and storage volume remains stable. Measuring backwash, reject, rinse and drain flows makes the remaining difference easier to verify.
Why is backwash flow difficult to measure?
Backwash may remain inactive for long periods and then rise quickly during a short cycle. The selected flow range, full-pipe condition, response and accumulated volume must cover the complete event.
Can an Electromagnetic Flowmeter be used on a reject line?
It may be suitable when the liquid has sufficient conductivity, the pipe remains full, the operating range is defined and the selected materials match the medium.
When can an Ultrasonic Flowmeter support a retrofit?
It may support selected existing water lines where pipe cutting is difficult and the pipe material, wall thickness, lining, fluid condition, straight run and mounting access are suitable.
Why must treatment and cooling totals use the same period?
Different reset times can make balanced flows appear inconsistent. A synchronized reporting period allows treatment, facility and cooling teams to compare the same operating window.
Make Data Center Water Recovery Verifiable
Treatment capacity shows how much water a system is intended to produce. A complete flow boundary shows how much raw water is used, where the remaining water goes and whether actual recovery matches the project expectation.
If your team is reviewing a similar measurement point, Velomac can help check the medium, flow range, pipe conditions, installation space, totalization and signal requirements before selection.